Tag Archives: wanstead

When did September become a summer month?

The answer is around 1993. A look back at mean temperature and rainfall statistics for east London over the past hundred years reveals that the ninth month has, since that date, slowly become warmer and drier.

Putting all the arguments of meteorological and astronomical summer aside, many people of a certain age regard September as an autumnal month, but as recent years have shown it can very often be an extension of summer; September 2016 was the second warmest on record in the local area, warmer than many previous summer months!

Looking back even further, over the past 100 years, the September mean has trended upward, though many peaks and troughs reveal how the month has ebbed and flowed from being summery to autumnal.

The prognosis to the end of this month suggests that air pressure will be anomalously high – so the pattern in the south-east for settled, summery weather in September doesn’t look like ending any time soon.

sept means
The September mean trend has crept generally upward.
sept rainfall
A look at rainfall back over the last 100 years shows that wet Septembers have been on a general decline since 1994.

sept chart.gif

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London’s September extremes since 1959

September in recent years has often been a more summery month than August. But this month in some years can see a rapid onset of autumn.

I’ve put together a few top 10s of stats for Wanstead, St James’s Park and Heathrow for the month of September.

september extremes

SJP september

heathrow sept

Some national UK September values according to TORRO

Hottest: 35.6C Bawtry, South Yorkshire – 2nd 1906
Coldest: -4.5C Dalwhinnie, Highland, – 26th 1942
Wettest: 190.7mm West Stourmouth, Kent – 20th 1973

In terms of climatology September maxima, considering the 1981-2010 average, shows a slight decrease through the month, though around the 1st and the 22nd there is often a spike. This would reflect the September singularities; early September warmth occurs in 82 per cent of years while the ‘Old Wives Summer’ has a 64 per cent probability.

september mean

 

The average rainfall graphic shows that downpour amounts are variable through the month. A tendency for dry weather to the 8th prevails before the trend increases, the wettest days usually 13th and 19th.

sept rain

 

 

August 2018: average temps, rain, sun

August was a big let down in a summer that saw the mean temperature nationally match the UK’s best-ever summers.

summer max 2018
Summer maxima took a real dip during the first week of August

The mean temperature finished 18.9C, 0.7C above average.

Some 69.5mm of rainfall was recorded, 139 per cent of the 1981-2010 average. Some 169 hours of sunshine were recorded, 87 per cent of average. Apart from being 1.5C warmer than average it was a carbon copy of last August.

To view full stats follow this link:http://1drv.ms/1kiTuzv

Summary for August 2018

Temperature (°C):
Mean (1 minute)  18.8
Mean (min+max)   18.9
Mean Minimum     13.8
Mean Maximum     24.3
Minimum          6.9 day 10
Maximum          33.1 day 03
Highest Minimum  19.1 day 03
Lowest Maximum   17.0 day 09
Air frosts       0
Rainfall (mm):
Total for month  69.5
Wettest day      13.6 day 16
High rain rate   48.3 day 10
Rain days        14
Dry days         17
Wind (mph):
Highest Gust     22.8 day 24
Average Speed    2.5
Wind Run         1841.7 miles
Gale days        0
Pressure (mb):
Maximum          1025.1 day 31
Minimum          1001.3 day 26
Total hours of sunshine        169

 

 

Summer 2018: second hottest since 1797

The results are in and statistics show that this summer was the second hottest in a local record going back to 1797. The mean temperature of 19.57C was 2.4C warmer than average, just six hundredths of a degree cooler than the summer of 2003.

A sustained period of heat that continued the theme of the hot late spring was enough to see a new entry into the hottest-ever list of heatwaves.  But the hottest weather was over by the end of July, August being very disappointing compared with the first two months of summer.

It was also the driest summer for 15 years. Just 87mm were recorded, that’s 60 per cent of average and just 7mm wetter than the historic summer of 2003, the year the UK’s highest temperature record was set.

It was the sunniest summer for 5 years: 663 hours of sunshine were recorded, over 100 hours less than 1976, the 24th sunniest summer since 1881.

Hottest day: 34.7C (26/7)
Coolest day: 17C (9/8)
Warmest night: 19.7C (26/7)
Coolest night: 6.4C (12/6)
Wettest day: 13.9mm (16/8)

summer max 2018

summer 2018 rain

Summary for period 01/06/2018 to 31/08/2018

Temperature (°C):
Mean (1 minute)  19.4
Mean (min+max)   19.6
Mean Minimum     13.7
Mean Maximum     25.5
Minimum          6.4 on 12/06/2018
Maximum          34.7 on 26/07/2018
Highest Minimum  19.7 on 26/07/2018
Lowest Maximum   17.0 on 09/08/2018
Air frosts       0
Rainfall (mm):
Total for period 86.9
Wettest day      13.9 on 16/08/2018
High rain rate   48.3 day 10/08/2018
Rain days        19
Dry days         73
Wind (mph):
Highest Gust     22.8 on 24/08/2018
Average Speed    2.6
Wind Run         5714.2 miles
Gale days        0
Pressure (mb):
Maximum          1029.9 on 21/06/2018
Minimum          1001.3 on 26/08/2018

July 2018: warmest month on record

July 2018 was the warmest month locally in a record going back to 1797. The mean temperature of 21.7C is 3.2C above the 1981-2010 average and exceeds the previous warmest July (1983) by 0.3C. Indeed, it is the warmest calendar month ever.

jul152018
MODIS image July 15th 2018

Just 16.7mm of rain fell, all of it coming after the 47 day long drought ended with a thunderstorm on the 27th. The amount is 38 per cent of average and is the driest July since 2010 and 7th driest in the local record.

There were 273 hours of sunshine, 142 per cent of average, making it the sunniest for five years and 10th sunniest on record.

As well as many hot days the lack of rainfall was most noticeable with catastrophic results on Wanstead Flats.

The warmest day occurred on the 26th with 34.7C.

The wettest day occurred on the 27th with 7.3mm falling.

 

 

40C in London end of July? Probably not

The long range weather models are causing much excitement on various forums with one run predicting an anomaly of +16C on Sunday, July 29th.

july29th

Such an anomaly would see temperatures exceed 40C in London, unprecedented looking back at records to 1841; the highest temperature recorded in the UK was 38.5C at Brogdale, near Faversham, Kent, in Augut 2003.

Though it is improbable it is not impossible. Back in April conditions allowed the temperature to rocket to a monthly record of 29.1C, a positive anomaly of 15.5C!
A repeat of similar synoptic conditions would be needed – these would obviously be helped by the record meteorological drought conditions this area is currently experiencing.

Because reliable thermometer records of heatwaves only go back as far as 1840 it is impossible to quantify whether 40C has ever been exceeded in the UK prior to then.

However, accounts of the heatwave of July 1808 suggest parts of England may have come close. Far removed from images of freezing Georgian winters and miserable summers the July of 205 years ago was among the warmest ever. The monthly mean for July 1808, according to the Central England Temperature series, was 18.4C – the 6th hottest July since the beginning of the series in 1659.

Luke Howard, the ‘father of meteorology’ who at the time lived in Plaistow, referred to the heatwave in his diary on July 13th: “Temperature at 9am 84F. The intense heat of the maximum lasted nearly three hours till about 4pm. At 6pm the temperature was 90F.” Another entry mentions a reading taken nearby. “Another at Plashet, a mile and a half eastward, indicated 96F as the maximum under the shade of a house.”

While Howard’s methods of measuring the temperature ran short of modern standards, his thermometer was hung under a laurel bush, the values still give a valid insight into the heatwave.

Tales of the heatwave, which particularly affected east and north-east England, can be seen in letters sent to local newspapers around the country. Many describe labourers dying from heat exhaustion while working in fields. Farm animals and horses suffered a similar fate.

One letter from Hull, published in the Coventry Mercury, said: “At Sigglesthorne, the honey in some beehives melted, ran out upon the ground, and most of the bees drowned in it. At Sutton, a lamb and a dog belonging to the Rev Mr Croft of Rowley, expired in the heat; and several birds dropped down dead, while flying over the streets of this town.”
Of course it is impossible to know about the health of people and animals that died but that birds dropped out the sky suggests extreme heat.

 

East London: drier than the Sahara desert

This summer has seen less than a millimetre of rain fall across our region, less than some parts of the Sahara desert!

The lack of precipitation has had catastrophic results, not least being a big contributing factor to the huge grass fire that swept through parts of Wanstead Flats at the weekend.

Since May 29th just 0.7mm has fallen in Wanstead, less than the 2.9mm recorded in Bechar, Algeria, and far less than Agadez in Niger which recorded nearly 108mm.

50 days

Of course the fact that the mean temperature of Wanstead over the same period is at least 13C cooler than both Saharan towns means that the dunes won’t be blowing across the Temple any time soon.

The affects of the dry weather can also be seen across the UK in these MODIS images, the lush greens of last year looking much paler and browner.

comparison

 

jul232014
MODIS image July 23rd 2014
jul152015
MODIS image July 15th 2015
jul192016
MODIS image July 19th 2016
jul172017
MODIS image July 17th 2017
jul152018
MODIS image July 15th 2018

 

 

 

London droughts back to 1871

A thunderstorm on July 27th has ended a dry spell that lasted nearly 7 weeks in east London. As storms go it was a fairly tame affair, just 1.3mm fell, the first rain in 47 days, 20 hours and 14 mins.

drought rankThere are many descriptions of drought but the one I am using here, for sheer simplicity of comparison back to 1871, is the definition used up until the 1990s; that is 15 consecutive days with less than 0.25mm (0.01 inches) rain on any one day.

Meteorological droughts occur in most years though obviously ones that occur in summer are far more noticeable than those in winter. Since 1871 there have been 35 calendar years where no drought has taken place.

The longest drought before this one in 2018, probably not surprising for those who remember it, occurred during the long hot summer of 1976. The fact that summer came on top of a very dry winter, rainfall that season was about a third of what was recorded here last winter, meant that water supplies were in a much worse state, with hosepipe bans common.

Other drought years to feature include 1959, which saw the 3rd sunniest summer on record, 1929 and 1995, a summer which saw one of the hottest heatwaves on record.

For the stats I’ve used local rainfall figures back to 1959 and then stats used at Kew to 1871.

individual droughts
This graphic shows droughts were most common between 2000 and 1921. Apart from this year the length of droughts seems to be declining

Looking at the results more closely I’ve divided them into their meteorological seasons.

spring drought

summer drought

autumn drought

winter drought

 

 

 

London’s July extremes since 1959

With the ultra dry and warm month of June many feel the rest of summer will remain hot and dry. Recent weather patterns have seen much high pressure to our north keeping us dry and mostly sunny but protected from any humid Spanish plumes.

A look at local east London stats shows that half of the last 10 July months have been warmer than average while only two have been much drier than average.

I’ve put together a few top 10s of stats for Wanstead, St James’s Park and Heathrow for the month of July.

july1959WAN

july heathrow

sjp july

Some national UK July values according to TORRO

 

Hottest: 19th 2006: 36.5C at Wisley, Surrey.
Coldest: 15th 1977: -2.5C at Lagganlia, Highland.
Wettest: 18th 1955: 279.4.8mm at Martinstown Dorset.

july av mxIn terms of climatology July maxima, considering the 1981-2010 average, shows a fairly steady increase through the month, though around the 17th there is often a dip before a warm end. This would reflect the July heatwave singularity which occurs every year at 80 per cent probability.

The average rainfall graphic shows that downpour amounts are fairly random from year to year. The driest days are the 1st and the 25th. july av rn

 

June 2018: driest on record since 1797

This June will probably be most remembered for the lack of rainfall throughout the month. I recorded just 0.7mm of rain over the 30 days – the driest June in a local record going back to 1797, 0.4mm less than the previous driest June in 1925.

fire
A fire on Wanstead Flats on Friday 29th was quickly extinguished thanks to the fire brigade

As I write this the area is now experiencing its 24th day of ‘meteorological drought’ conditions with little prospect of anything heavy anytime soon. The month was in stark contrast to May which saw may downpours associated with thunderstorms.

It was a warm month. The mean temperature finished 18.1C, exactly 2C above average, though slightly down on last June and the 7th= warmest since 1797.

Some 231.4hrs of sunshine were recorded, 130 per cent of average, making it the sunniest May for 8 years, and the 30th sunniest since 1881.

The warmest day occurred on the 25th with 30C.

The wettest day occurred on the 9th with 0.4mm falling.

Summary for June 2018

Temperature (°C):
Mean (1 minute)  17.7
Mean (min+max)   18.0
Mean Minimum     12.3
Mean Maximum     23.8
Minimum          6.4 day 12
Maximum          30.0 day 25
Highest Minimum  17.8 day 18
Lowest Maximum   17.9 day 04
Air frosts       0
Rainfall (mm):
Total for month  0.7
Wettest day      0.4 day 09
High rain rate   4.0 day 09
Rain days        1
Dry days         29
Wind (mph):
Highest Gust     18.3 day 14
Average Speed    3.1
Wind Run         2199.7 miles
Gale days        0
Pressure (mb):
Maximum          1029.9 day 21
Minimum          1008.2 day 14
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        231.4
Elsewhere in the UK it has been a very dry month across England.
0-25
Two CET stations, Rothamsted and Pershore recorded 2.2mm and 10mm respectively.
Other stations:
Northolt 0.8mm
St Bees Head: 25.2mm
Scilly: 7.6mm
Shoebury: 0mm