There was much talk yesterday about a lot of the south of the England recording an ‘ice day’.
In the London area most places missed out because the temperature rose briefly above freezing around dusk and also just before the 0900 observation today.
So although it felt brass monkeys out there it doesn’t count.
Ice days are when the temperature fails to rise above -0.1C over a 24 hour period, usually from 0900 to 0900. The confusion over yesterday’s ice day was caused by the fact that some stations release a 06-18 maximum reading – both Kenley and Shoebury stayed below zero in this time period.
Ice days in the Wanstead area are probably even rarer than decent snowfalls. Since 1959 there have been 81 ice days.
The last time the temperature failed to rise above 0.0C was January 20th 2013. The last time the temperature failed to rise above -0.1C (a true ice day) was January 6th 2010.
Over a dozen stations stayed below freezing for 24hrs to 09z on January 27th
Stephen Davenport’s synoptic analysis of the event is included below:
“[The cold conditions were] all thanks to this nicely (or not nicely, depending on your view) blocked situation. On Tuesday 24th a 500 hPa ridge started build northeastwards to the north of a small upper low situated over France. By 12z on Wednesday 25th it had cut off to leave a classic-looking Rex block over western Europe:
Surface winds from the Continent started to bring colder air across as the temperature anomaly analysis for 12z Wed 25th shows, while milder southerlies continued across Ireland and Scotland, and brushed western Wales and SW England:
By 12z Thursday 26th the block was becoming more omega-like…
… and cold air continued to percolate north-westwards from the Continent farther across the British Isles:
There’s a certain beauty in the sinusoidal flow around a Rex block, I always think.”
December 2016 was the driest 12th month in over 80 years and the 5th driest in a record going back to 1797.
Christmas day was the second warmest on record in London
The total fall of 8.3mm is just 16 per cent of what normally falls in December, marginally more than December 1933. The mean temperature of 6.1C was 0.5C above average, though 4C colder than the record December last year.
There were 51hrs of sunshine, that’s 125 per cent of average.
The wettest day was on the 10th when 5.2mm of rain fell. The warmest day occurred on the 9th with 14.2C recorded. The lowest temperature occurred on the 28th when the spirit fell to -4C.
The sunniest days were on the 4th and 29th when seven hours of sunshine were recorded.
Air frosts: 8, Ground frosts: 14
Fog, frost and black ice all featured during December
Though January has started on the chilly side in the short term the weather will turn mild. Beyond that there is a suggestion that the weather could turn on the colder side of average with some models suggesting a cold snap with snow around mid-month.
My usual method of prediction to the end of the month has been scotched by the very dry December. The only years that were similar were both far colder than last month – the usual pattern of a dry month being cold or very cold was broken.
With the unprecedented warmth at the North Pole, last year’s odd behaviour of the QBO and a weak polar vortex we are in unprecedented territory in terms of what could happen later in January. My hunch, though, suggests the month will end up average to rather cold with little precipitation. Any cold spell with probably be the short-lived variety with a couple of inches of snow that lasts three days.
So, to sum up, we’re looking at a mean of 4.4C, rainfall: 55mm, sunshine: 39hrs.
In view of the above my forecast last month was very poor: predicted mean 4.4C (result 6.1C). Rainfall: 55mm (result 8mm). Sunshine: 39hrs (result 51hrs)
I have also published a winter forecast covering the London area that you can find here.
Here follows the full weather diary for December…Full stats for the month here:http://1drv.ms/1rSfT7Y
1st: Sunny start though the frost lifted readily into low cloud and mist to leave a chilly afternoon.
2nd: Cloudy, quiet and cool weather all day.
3rd: Cloudy and quiet all day. Feeling cold.
4th: Sunny , frosty start. Quickly warming up to leave sunny, cloudless afternoon.
5th: Sunny start, then patchy cloud – this thickening before becoming foggy overnight.
6th: Misty start after fog overnight. Cloudy most of the day though there was a brief clearance around midday.
7th: Cloudy most of the day though there was occasional brightness.
8th: Dull day though with a little limited brightness early afternoon.
9th: Cloudy but wth more brightness than yesterday. Very mild. Cloud thickened with light rain around 11am. This gradually grew heavier as the day progressed and was moderate overnight.
10th: Bright start and feeling mild, then cloudier and damp.
11th: Cloudy and dull all day.
12th: Dull all day with light rain early and late. Clearer spells overnight but overcast again by dawn.
13th: Dull with bits and pieces of drizzle up to 11.20am.
14th: Bright start with lots of cirrus and altocumulus – this gradually cleared to leave a warm and pleasant afternoon.
15th: Dull and cloudy with limited brightness.
16th: Dull and cloudy start.
17th: Foggy and dull all day.
18th: Misty start with fog above 90m on cycle ride. Then dull and grey all day. Mild.
19th: Dull and cloudy all day – some spots of drizzle.
2oth: Sunny start but clouded over late morning. Cloudy thereafter with some drizzle overnight.
21st: Cloudy start then sunny. Cloud returned and turned dull and dreary in the afternoon with odd drizzle.
22nd: Bright, misty start
23rd: Cloudy start with breeze beginning to build as a result of Storm Barbera.
24th: Cloudy and dull all day. Very mild. Temp increasing overnight with approach of warm front .
25th: Cloudy, breezy start. Remained dull all day though brightness was seen over the Thames and North Downs, disrupting the SW’ly flow.
26th: Sunny, hazy start and turning colder.
27th: Sunny, frosty start, the air pressure record of 2012 has been broken.
28th: Foggy start, the fog persisting to late morning before sun broke through leaving a chilly afternoon. Frost returned quickly after dark, a clear night.
29th: Sunny and very cold and frosty start. Frost returning after dark with fog forming in the early hours.
30th: Foggy and dull all day, the fog thickening up at nightfall. Approaching cloud lifted the fog and temperature.
31st: Dull and overcast to start – this sticking around all day.
This year finished as the 14th warmest on record – some 0.5C warmer than the 1981-2010 average – though 0.2C cooler than 2015.
Only four months of 2016 were below average temperature-wise
Six months of 2016 were roughly average – the means being within +/-0.7 every month, bringing the mean temperature to 11.7C.
Rainfall was less remarkable with the year being a little drier than average. The total of 561mm (93% of 1981-2010 average) puts it as the 122nd wettest since 1797, just 8mm wetter than 2015.
It was also a slightly duller than average year with 1,390 hours of sunshine recorded. That’s 93 per cent of average, the 92nd sunniest since 1881 – the least amount of sunshine for 12 years.
Earthquakes in Italy and early season snow cover in Siberia have been well documented in 2016.
They were also mentioned by Luke Howard in his publication The Climate of London in 1810.
He also mentions winter thunderstorms over the Yuletide period, from Christmas Eve to Boxing Day – the amount of rain overflowing the Thames.
24th: Very windy night with heavy rain. 25th: Wind high all day with rain frequent lightning in the evening from SE. 26th: Wind very boisterous early in the morning day fine the rain of the last three or four days being impeded in its passage to the Thames by the spring tides overflowed the banks and filled the marshes.
Within two days of this wild and wet spell, complete with strong north-westerlies, the wind swung north and then north-easterly to usher in 1811 with a 12-day cold spell.
The conditions of the cold spell were not severe, the coldest night was -8C, it was a pretty standard cold spell for the time and one that the south-east used to experience with fair regularity in the early to mid 1980s.
Models currently show a (fairly) narrow chance of a stormy Christmas period. It would be interesting if it were followed with a cold spell in January – just like the ones we used to get in 1980s.
* The Booty website also contains the following on that notable month…
What is thought to be Britain’s strongest tornado occurred in December 1810. A category of “T8” (on a ten-point scale) occurred on the 14th at Old Portsmouth. The TORRO website says it: “tracked from Old Portsmouth to Southsea Common causing immense damage – although no deaths, it is believed. Some houses completely levelled and many others were so badly damaged that they had to be demolished; chimneys were blown down and the lead on a bank roof was ‘rolled up like a piece of canvas and blown from its situation’.”
November 2016 was the sunniest in a record going back to 1881. Some 91 hours were recorded, 156 per cent above average and a complete contrast to last November which was the dullest for 47 years.
The temperature in the early hours of the 30th fell to -6.1C, colder than any night last winter and the coldest since January 2013
The mean temperature for the month finished 6.4C, that’s 1.5C below the 1981-2010 average ; 4C cooler than last year and the coldest November since 2010. The warmest day occurred on the 15th with 15.9C recorded. The first air frosts of autumn were recorded. The lowest temperature occurred on the 29th when the spirit fell to -6.1C.
Rainfall was 135 per cent of average with 80.1mm recorded. The wettest day was on the 19th when 23.5mm of rain fell.
The sunniest days were on the 2nd, 13th and 25th when eight hours of sunshine were recorded.
Air frosts: 4, Ground frosts: 19
The dolphin-shape of this radar image shows Storm Angus before it hit the south coast. The system stayed far enough south of us not to cause any damage in London
What has December got in store weatherwise? The models suggest the high pressure that has been anchored over us, bringing cold nights, will pull away to the continent. This will allow an ever milder but mostly dry source of air off the Atlantic through to mid month. Days will grow milder while frost and fog will feature less at night.
Beyond the grasp of the models my long range outlook method suggests an coldmonth is most likely at 43 per cent probability. Average comes in at 29 per cent probability while rather mild and rather cold are both 14 per cent probabilities.
Rainfall looks finely balanced. Wetter and dryer than average both come in at 43% probability while average is 14 per cent. Given the influence of high pressure at the beginning of the month I’m inclined to think it will be a drier than average month.
So, to sum up, we’re looking at a mean of 4.4C, rainfall: 55mm, sunshine: 39hrs.
My forecast last month was good: predicted mean 6.8C (result 6.4C). Rainfall: 55mm (result 80mm). Sunshine was way off, however – predicted total: 41hrs (result 91hrs)
I have also published a winter forecast covering the London area that you can find here.
Here follows the full weather diary for November…Full stats for the month here:http://1drv.ms/1rSfT7Y
1st: Cloudy and mild all day. Patchy drizzle at times.
2nd: Sunny, cold start after first ground frost of the autumn.
3rd: Sunny, cold start with cirrostratus and cumulus drifting around. Cloud thickened through the afternoon with some light rain around 9pm.
4th: Cloudy, dull start up to 11am. Rain pushed in and lasted for much of afternoon, clearing in evening.
5th: Cloudy, cold and damp start. Some brightness though with a cold wind.
6th: Sunny, cold start, tending to cloud in. Rain after 3pm. Feeling cold but too windy for a frost overnight.
7th: Sunny, cold and very breezy to start, the cloud tending to fill in through the day. Clearer overnight though too much cloud and occasional air prevented an air frost.
8th: Sunny and cold start. Cloud thickened during the day to bring rain after dark at 8pm that then fell through the night – the biggest fall since Brexit day.
9th: Light rain slowly clearing to cloud.
1oth: Cloudy start with light rain showers around 10.30am then cloudy. Some sunny intervals in the afternoon. Milder.
11th: Bright start with cloud decreasing through the morning to leave a pleasant and clear afternoon.
12th: Miserable and rainy to start, this lasting past 11.15am. Drizzle thereafter into 6pm.
13th: Sunny start though cloud tended to fill in through the day. Damp overnight with patchy drizzle.
14th: Cloudy and damp start with some breeze. Brief brightness at noon but patchy drizzle moved in around 4pm.
15th: Cloudy and miserable though very mild.
16th: Sunny start and very mild though cloud tended to fill in during the day making the sunshine milky.
17th: Bright, breezy start, the breeze increasing until a squall blew through at 2.40pm then sunny spells.
18th: Bright start with milky sunshine then tending to cloud over. Feeling cold.
19th: Bright sunshine though cold to start. Patchy altocumulus developed through the day, leaving it to become bright, the strength of the sun diminishing. Rain started around 6pm and fell through night with varying intensity.
20th: Dull and cloudy start with rain returning at 10am. Cloudy afternoon with rain returning late evening and through the night, some heavier bursts.
21st: Cloudy with showers past noon. Heavier showers moved in mid afternoon and fell into the evening.
22nd: Cloudy with a few very light showers around. Breezy.
23rd: Cloudy and breezy. Feeling mild.
24th: Cloudy and mostly dull with brief brightness at noon.
25th: Sunny with just a few cumulus around.
26th: Sunny start but low cloud blotted out the sun around midday then cloudy and cool.
27th: Cloudy and mild.
28th Sunny all day with just a few cumulus floating around.
29th: Sunny all day with frost persisting on grass in shade.
30th: Sunny and very frosty start. Frost persisting on the grass all day with a very cold start to the night. A veil of cloud crossed the region late evening, lifting the temperature above freezing, before clearing before dawn
Frost still lingers on my lawn as I write this winter forecast on the last day of the meteorological autumn. Last night’s minimum was -6.1C, the coldest night this year and, indeed, colder than any night last winter.
It would be very easy to get caught up in the hysteria that happens every November of what the winter will bring. Most of the hysteria comes from ‘coldies’, those folk that hope every winter will be the coldest and snowiest on record. I count myself among them.
The north-west of England looks around 10C above average on December 9
But, despite hints from BBC weather forecasters that something maybe afoot in terms of something colder than usual from mid-December, years of disappointment have taught me to just take winter as it comes. Meteorological models this morning look anomalously warm for the first half of December, the UK being on the warm side of an anticyclone centred over France – the theme of so many winters I can remember.
The current phases of ENSO and QBO suggest that their influence on our winter this year will be far less marked than last year. Looking at teleconnections with a slight La Nina and the current QBO cycle have revealed winters that were fairly uninspiring though by no means write-offs for snow, two examples in the case of QBO being 1985/86 and 1990/91 – both had very cold Februaries.
Before I got too bogged down with trying to find patterns here I decided to move on to my more traditional pattern-matching.
Before I trawled through the figures my initial gut reaction to this winter was that it would be the coldest for at least four years – a not-too-difficult feat giving the mildness of the last three winters which saw very little in the way of snow.
The overall mean temperature for December, January and February came out at as4.2C – 1.2C colder than the 1981-2010 average, with average precipitation.
A rather cold winter, over three months doesn’t tell you much. A very mild and stormy December could mask a dry and notably cold February. This makes it worth looking at the individual months of each winter.
There is a lot of spread in the above tables. Considering them altogether I would guess winter will unfold in the following way:
December to start mild, possibly becoming very mild, before beginning to turn very cold mid-month. This pattern will persist, with varying intensity through into January which could also be very cold. Milder conditions to follow in February though this will probably end a fairly average month and drier after a slightly wetter than average December and average January.
As well as my method of using rainfall and temperature I also considered other methods. One was Russian research that states that the weather pattern in the winter will be the opposite to the weather on September 17th and November 7th. This autumn September 17th was N’ly and November 7th was NNW’ly. So, this would suggest a continental flow from S and SSE.
You can read the method of how I reached my conclusion here.
The Met Office’s latest outlook for a relatively high chance of cold weather in the early part of winter has set the internet abuzz with talk that the UK is about to experience its coldest winter in years.
The 3-month outlook, produced by the agency for contingency planners, states:
Lower-than-average temperatures are more probable than higher-than-average values. Overall, the probability that the UK-mean temperature for November-December-January will fall into the coldest of our five categories is 30% and the probability that it will fall into the warmest of our five categories is 10% (the 1981-2010 probability for each of these categories is 20%).
THe ‘30% chance’ for temperatures to be in the coldest of five categories is more significant than it would appear: in this three-year period of mild winters that figure usually hovers far lower.
The continent is not yet cold enough to get excited about this synoptic chart for Monday, November 7th
The Met Office’s method, which includes a combination of data such as QBO, ENSO and ground based observations also agrees with my own method of finding local October singularities back to 1797. This month I found that an average or cold November is most likely: average and cold are both 30 per cent probability. Rather cold and severe are both 20%! There appears no chance of anything mild.
So, we can look forward to ‘a reduction in the normal westerly flow across the UK from the Atlantic, with a greater frequency of northerly or easterly winds’.
But what does this mean for the London area? If the near continent is not cold enough northerly and easterly winds could just bring a succession of cold rain in the form of showers off the North Sea with a higher than average frequency of frosty nights: nothing out of the ordinary for a slightly cooler than average November.
To try and second guess proceedings into December I decided to plot all year singularities to find when the cold spells would most likely fall and how severe they could be.
The results for November look unexciting: the coldest day is likely to be around the 19th with a maximum of 6.9C. The best chance for something cold looks to be in December, around 6th to the 11th – but there again highs of 3C or 4C would mean that any snow would be short lived. There appears to be a warm up in time to scotch hopes of a white Christmas before another cool down toward new year.
So, in conclusion, late autumn / early winter is likely to be a lot colder than the past three years. It is perhaps this fact, together with frosty mornings being common, that will make the season feel colder than it actually is.
I will be publishing my usual winter forecast on December 1st.
The coldest day in November is likely to be around the 19th
October 2016 was yet another dry month, a pattern that has emerged since the middle of June. Just 52 per cent of the October average was recorded.
October saw many pleasantly sunny days
The monthly mean finished 11.5C, 0.3C above average and ending a three-month run of warm temperatures.
Some 105 hours of sunshine were recorded, 98 per cent of average
Air frosts: 0, Ground frosts: 0
So what has November got in store weatherwise? The models on the 1st suggest an anticyclone anchored to our west over the Atlantic will bring a regime of, at times, chilly northerly winds and the potential for rainfall, much probably in the form of showers, driven by low pressure in the North Sea. Where skies clear at night there will be potential for the first air frosts of the autumn.
Beyond the grasp of the models my long range outlook method suggests an average or cold month is most likely: average and cold are both 30 per cent probability. Rather cold and severe are both 20%! There appears no chance of anything mild.
Rainfall appears that it will be skewed toward something above average at 40 per cent, though average and below average are both 30 per cent.
Sunshine looks average at 57 per cent probability.
So, to sum up, we’re looking at a mean of 6.8C, rainfall: 55mm, sunshine: 41hrs.
Numerous holes dug by squirrels appeared in October. The squirrels have no more an idea than we do whether winter will be cold
Here follows the full weather diary for October…Full stats for the month here:http://1drv.ms/1rSfT7Y
1st: Rainy start with showery bursts to 11.25am then through afternoon mostly cloudy.
2nd: Sunny but chilly, feeling very autumnal. Clearing into the evening with a cold night to follow.
3rd: Sunny, gin clear all day until 2.08pm.
4th: Another sunny albeit slightly hazy start then patchy cumulus. Warm in the sunshine even with a easterly breeze.
5th: Sunny start though breezy and with quite a few cumulus around. Cloud streets observed at 10.30am, the cloud tending to decrease and completely melt away by 4pm.
6th: Sunny start but with much cloudier spells at times. Warm in the shelter.
7th: Cloudy all day, the cloud thick enough at lunch time for drizzle that damped the ground.
8th: Cloudy with bursts of light drizzle in the morning, some brightness. A heavy shower at 2pm was brief then cloudy. Clear and cold overnight.
9th: Sunny until 2pm with patchy cumulus – a really glorious morning. Sunny spells in afternoon with cold night to follow.
10th: Sunny with just patchy cirrus first thing. Thick patches of alto-cumulus drifted across from time to time. Cold overnight.
11th: Sunny with patchy cumulus which melted away through the day. Showers after dark, one at 2330z.
12th: Cloudy and damp start. Short, sharp shower at noon then mostly cloudy.
13th: Rainy , wet start thanks to a streamer of moderate to heavy showers.
14th: Cloudy am but with lots of sunshine mid-morning before clouding over again though staying bright.
15th: Bright start but with lots of cloud pushing in and light burst of drizzle at noon. Cloud thickened before rain moved in after 5pm and fell intermittently through the night.
16th: Damp start as the remnants of the overnight rain cleared away, then becoming brighter at 11.15am. Sunny spells for a time before turning cloudier with some very sharp showers on yet another convergence line.
17th: Cloudy start but soon brightening up with some pleasant sunny spells. Heavy burst of rainfall at 5.30pm with more showers at midnight and early hours.
18th: Cloudy though quickly turning bright and breezy with long sunny spells after clearance of the cold front.
19th: Bright start though more cloud around than sun all day. Feeling colder than of late.
20th: Bright and breezy with variable cloud and sunny spells. A short shower at 2pm damped the ground. Clear spells overnight made it chilly. A shower at 9.30am.
21st: Cloudy and chily start.
22nd: Cloudy and cold start, brief clearance at 11am then sunny spells.
23rd: Sunny and clear to start though cold. Sunny spells into the afternoon. Cloudy overnight.
24th: Cloudy and cool during the day and overnight.
25th: Dull and cloudy with only limited brightness. Clear early evening with temp falling before it turned misty. Cloud pushed in raising the temperature.
26th: Cloudy start and turning very dull before bright spells spread in at noon.
27th: Cloudy though getting brighter through the morning with a brief clearance at noon, then bright and sunny intervals.
28th: Sunny and very mild to start. Sunny spells through the day.
29th: Cloudy start with bright intervals after midday. Clear spells after dark with fog forming after 11pm which gave a foggy start.
30th: Foggy start then cloudy and miserable.
31st: Fog to start then clearing at 11am. Gorgeous sunny day thereafter.
Sections of the tabloid media have been going into overdrive these past couple of weeks with tales that the UK will soon be in the grip of an Arctic freeze – one headline in the Daily Express boasted that parts of the UK were in for FOUR MONTHS OF SNOW.
The Daily Express ‘forecast’ was published at the end of September
These stories are nothing new though they seem to be published earlier and earlier in the autumn. By the time we reach November – once the traditional time when winter forecasts started appearing – the tabloids have already turned their attentions to spring. Much of it is just ‘clickbait’ – a means for publishers to prove their stories are being read to keep their advertisers happy, a symptom of an industry in financial dire straits.
There will be snow somewhere in the UK during the next five months but predicting heavy snowfall in a given area, such as London, is impossible. But given the outrageous claims at such a long way from the start of the season on December 1st I decided to have a look to see if there is anything wintry on the horizon.
I started by comparing a range of historic datasets, including quasi-biennial oscillation (QBO) and el niño–southern oscillation (ENSO), against monthly mean temperature and rainfall anomalies. Because ENSO data only goes back to 1950 the findings are obviously far more restricted than my winter forecast method which uses local data going back to 1797.
The results of my data trawl are underwhelming. The best fit years were as follows:
For anyone who likes snow the above is not encouraging, however, given the past year which has seen several daily and monthly records shattered, including a record warm December, who’s to say that recent warm temperatures will suddenly swing the other way.
The above table would also suggest that the coming winter will be colder and snowier than the previous three – but that gives little away given how mild the past three winters have been.
October 2016 has seen a strong blocking high become established over Scandinavia, the earliest this has happened since 1881.
A study of mean temperature anomalies in London since 1950 suggest that sudden swings, both positive and negative, are becoming more likely. Last month was the fifth month in a row that I recorded a positive anomaly – the longer this goes on the more likely it is the mean could turn negative – though bear in mind that I have recorded 12 months in a row of positive anomalies, from February 2011 until January 2012.
Current weather also suggests that something maybe afoot with the earliest establishment of a strong anticyclone over Norway (the fabled Scandinavian high) since 1881! This weather pattern gives the south-east its best chance of snow with the feed of cold air often coming all the way from Siberia. Time and again, however, I’ve seen these patterns break down in November just as everyone starts talking about an imminent severe winter. There is more than an element of truth to the saying:
Ice in November to bear a duck, rest of winter will be slush and muck
In conclusion, while the early figures look bleak for snow in the low-lying south-east, it is still far too early to tell if the coming winter will be mild or cold.
Last month was the second warmest September in a local record going back to 1797! The monthly mean finished 17.8C, 2.4C above average. Despite being an ‘autumn’ month September was actually a full degree warmer than June!
September 2016 was the second warmest in a local record back to 1797, though we’re talking by fewer than tenths of a degree.
The hottest September day since 1959 was recorded on the 13th when 33.1C was reached, the sixth equal hottest in the local daily record back to 1848.
The month also saw the warmest minimum recorded since 1959 when the mercury failed to fall below 18.7C on the 6th.
It was another very dry month, the third much drier than average month in a row: just 27.7mm fell, 24 per cent of average, making it the driest September since since 2007 and the 12th driest in the local record.
Like August, the month only falls down in terms of impressiveness when sunshine hours are considered. Some 119 hours were recorded, that’s 85 per cent of average, making it the dullest September for 15 years.
Air frosts: 0, Ground frosts: 0
So what has September got in store weatherwise? The models on the 1st suggest that a large Scandinavian high will become established to our NE bringing lots of settled weather and showers on coasts. There’s obviously the chance of trough disruption as the month progresses if the anticyclone’s influence declines.
Beyond the grasp of the models my usual long range outlook method falls down this month due to September’s warmth and dryness – there is nothing within +/- 10% of September’s statistics. I would guess, however, that we are looking at another drier than average month with frost becoming a risk as the month progresses where skies clear. There is also the chance of more pleasant autumn days where skies are clear during the day.
My September outlook for temperature was poor. I predicted a mean of 15.3C (outcome: 17.8C). It was much, much drier than I thought: 300mm (outcome: 27.7mm). Sunshine was poor: 140 hours (outcome: 119 hours).
Here follows the full weather diary for September…Full stats for the month here:http://1drv.ms/1rSfT7Y
1st: Sunny start but cloud gradually increased until it was overcast by 6pm. Clear spells overnight but warmer than previous nights.
2nd: Cloudy though some brighter intervals.
3rd: Sunny start, cloud began to pile in at 12.30pm with rain arriving at 5.30pm, this fell through the evening with some showers in the early hours.
4th: Bright, breezy start but rapidly turning cloudy and dull. Some rain overnight.
5th: Light rain and dull to start – this quickly clearing to cloud by 3pm. Things remained cloudy with a muggy night.
6th: Cloudy, dull and muggy start after warmest September night on record. Another warm night though muggy.
7th: Cloudy to 11am though sun breaking through as drier air arrived. Feeling humid.
8th: Sunny start but with plenty of cumulus, this quickly decreasing to leave clear sky.
9th: Cloudy morning though sky seemed to periodically clear of low cumulus before becoming overcast and very breezy in the afternoon. Some rain overnight and just before obs time.
10th: Cloudy start with patchy light rain, this briefly turning heavy at 1pm before turning occasionally moderate. Dreadful afternoon after recently. Clearing overnight to leave a sunny start.
11th: A glorious sunny day with only the odd patch of cirrus.
12th: Bright start with some sunshine, clouding over with a few splodges of rain with warm front. Then sunny and very warm.
13th: Sunny start with a few cirrus and castalanus around. Breezy at times with the thermals. The warmest September day since 1959 and 6th equal warmest since 1848.
14th: Sunny start with a few cirrus. A few patches of alto-cumulus later. Very warm but not as hot as yesterday. Warm, pleasant evening. 15th: Sunny with a few wispy cumulus, clearing to hot sunshine. Some alto-cumulus developed at 2pm and towering cumulus could be seen in distance. Thunderstorms reporting to NW of London. Cloudy and warm overnight with eight peals of thunder in the early hours and heavy rain.
16th: Light to moderate rain through the morning, petering out at 1.30pm.
17th: Cloudy, cool and breezy all day, at times dull.
18th: Cloudy all day, a bit warmer than the previous two days.
19th: Cloudy start though with sun breaking through briefly at 11am until 1pm then cloudy again. Rain at 1am that didn’t last long enough to register.
20th: Cloudy and fairly calm – a nothing day with odd very light drizzle.
21st: Bright start with cloud breaking to long spells of sunshine before more cloud moved in. Warmer than of late.
22nd: Cloudy but sun broke through giving pleasant afternoon and cool overnight.
23rd: Sunny, gin clear and cold start. Just a few fair weather cumulus through the day.
24th: Sunny start with cloud decreasing. Very warm in sun but cloud and breeze built through the day. Overnight light rain between 6am and 9am.
25th: Bright start after overnight light rain.
26th: Bright start with a few cloud breaks here and there. Heavy shower at 12.15pm with further threat of rain but stayed dry.
27th: Bright start with signs of a cold front moving in from south then cloudy.
28th: Sunny start with patchy cirrus, this tending to thicken at lunchtime to turn mostly overcast with humidity increasing. Breeze also picked up with reappearance of sun mid afternoon. Cloudy, very mild and breezy rest of the day.
29th: Cold front and brief heavy rain swept in at 10.03am. Then intermittent falls until 11.23am.
30th: Sunny, gin-clear start, patchy cumulus bubbling up at 10.30am. Cloud grew thicker around 12 noon with brief shower at 1pm. Then sunny spells and cloudier periods. Another shower just after nightfall then clear. Cloud moved in after 2am with another shower. Early sunshine gave way to moderate showers around 9.45am.
The overall mean temperature for December, January and February came out at as
Wanstead Meteo 
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