August 2019: warmest for 4 years

Apart from the hot four days in the last week August 2019 was fairly unremarkable.

Overall the monthly mean finished 19.9C, that’s 1.4C above average.

Rainfall at 37.7mm, was 75 per cent of average,  the driest for 3 years. Sunshine, at 180hrs, the sunniest for 3 years.

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

august max

Summary for August 2019:

Temperature (°C):

Mean (1 minute)  18.9
Mean (min+max)   19.3
Mean Minimum     13.9
Mean Maximum     24.7
Minimum          8.8 day 20
Maximum          32.6 day 27
Highest Minimum  19.5 day 07
Lowest Maximum   17.9 day 14
Air frosts       0
Rainfall (mm):
Total for month  37.7
Wettest day      12.6 day 14
High rain rate   65.8 day 09
Rain days        11
Dry days         20
Wind (mph):
Highest Gust     22.1 day 10
Average Speed    2.6
Wind Run         1941.4 miles
Gale days        0
Pressure (mb):
Maximum
Minimum
Days with snow falling         0
Days with snow lying at 0900   0
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Two Paris heatwaves two centuries apart

In July 1808 Paris wilted in a heatwave. The average maximum for the 13-day spell that began on the 10th was 31°C, higher than a similar spell last month that saw the all-time record for the French capital broken.

The temperature at the peak of last month’s hot spell reached 42.6°C, some 6.4°C higher than the peak of the 1808 spell but, as the graph below shows, maxima fell back more quickly than 1808.

paris heat line

The more ‘pointed’ nature of maximum temperature during the spell last month backs up findings of the changing jet stream;  the wriggly nature amplifying the heat.

Tmin

mean

The average mean and minimum temperature of both spells showed a difference of just 0.2°C.

Since Paris recorded its hottest day ever there have been just two days where the temperature has exceeded 30°C.

paris july 1808
The values for the 1808 spell were listed in Luke Howard’s Climate of London.

The heat in Paris in 1808, like in 2019, was also felt in London. Luke Howard noted the following in The Climate of London.

“Very hot from July 12th to 19th. On the 12th a thermometer in perfect shade in a window in St James’s Park was 81.5 degrees at 3pm, and on the 13th at the same hour, 94 degrees. On the same day four men and seven women were killed by sunstroke in various parts of the Midland counties, and numerous coach and other horses were also killed. On the 15th a very violent and destructive thunderstorm in Gloucestershire, Monmouthshire, and surrounding counties.”

* Values for 2019 were taken from the station Montsouris.
** Though there is no way of knowing how accurate the 1808 values were previous studies have found that historic temperatures can be as much as 3°F too high.

July 2019: a new Tmax record

July 2019 saw the month’s daily maximum record broken on the 25th with a high of 36.8C, The reading beat the previous record set on July 1st 2015 by 0.8C and was the second highest reading recorded in this area. Cloud that drifted in mid afternoon put paid to any chance of all-time record though Cambridge, further north, managed to break the UK record with a reading of 38.7C. This temperature set in the Botanic Gardens beat the previous record of 38.5C set in Brogdale, Kent, in 2003.

 

north
The weather enclosure in the Cambridge Botanic Gardens meets WMO guidelines

Although it has been mentioned that the Cambridge site appears to be overdeveloped it meets the WMO standard and the Met Office are happy with the record.

Compared with 2003 the heat this time was far more widespread and further north, with many stations recording higher values than 2003, as shown by these 24 hours to 6pm readings below.

 

In 2003 some 44 stations recorded 30C or above whereas this year some 67 reached 30C or higher.

Though the heat was record breaking it was much shorter lived than 2003. Like last month and July 2015 the 9-day temperature trace is far more ‘pointed’ – perhaps a symptom of the changing behaviour of the jet stream.

Overall the monthly mean finished 19.9C, that’s 1.4C above average though 1.8C cooler than last July – the warmest month on record.

Rainfall at 61.5mm, was 141 per cent of average,  the wettest for 2 years. Sunshine, at 165hrs, is 85 per cent of average and well down on last July’s 273hrs.

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

2019july
‘Feels like’ maxima.
juky feels
June 1981-2019 maximum anomalies
july all.PNG

 

The 12 month rolling rainfall total is…

Summary for July 2019

Temperature (°C):
Mean (1 minute)  19.8
Mean (min+max)   19.9
Mean Minimum     14.7
Mean Maximum     25.1
Minimum          9.2 day 03
Maximum          36.8 day 25
Highest Minimum  19.6 day 23
Lowest Maximum   19.5 day 27
Air frosts       0
Rainfall (mm):
Total for month  61.5
Wettest day      20.6 day 19
High rain rate   16.1 day 18
Rain days        10
Dry days         21
Wind (mph):
Highest Gust     16.8 day 20
Average Speed    2.2
Wind Run         1664.1 miles
Gale days        0
Pressure (mb):
Maximum          1029.0 day 03
Minimum          1004.8 day 30
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        0.0

The night London slept out in the heatwave

Sleeping in heatwaves is never a great prospect even in an age where fans and air conditioning units are becoming more and more common.

In 1948, however, residents of Kensington and other areas of London were so hot and desperate to escape oven-like houses caused by temperatures well into the 90s that they decamped en masse into the streets and local parks to get some kip.

A report published in the Aberdeen Journal on Friday 30th July describes how folk down south were coping with the heat.

“The metropolis last night was like a large restless household—with all the lights ablaze, doors and windows thrown open, the family fretful, and endless pots of tea brewing far into this morning.

aspro heatwave ad Yorkshire Post and Leeds Intelligencer - Wednesday 13 August 1947“Perhaps one in ten among the 8,000,000 of us slept after midnight. For the rest, we tossed and turned and saw out this heatwave night, when temperatures were never below 71 degrees, a variety of ways. About midnight I walked past the gaunt old Edwardian mansions in Kensington. With the exception the lights that burned from every window, the scene was reminiscent of the early days of the Blitz.

“Families trekked across the roadway in varying stages of undress to their little bits of ornamental gardens. With them went camp beds, bed linen, umbrellas, “in case,” the children, and the household pets, choose a cool open-air camping spot and feel wonderfully adventurous and spartan in the process.”

“At regular intervals the adolescent members of the squatting colonies were dispatched to the tea and coffee stalls on the corner, and perhaps for the first time in years these traders ran out of stocks. On the Kensington-Chelsea boundary, where life becomes noticeably less inhibited and on occasions less swish, a mixed group of young artists was sleeping on the pavement off Fulham Road.

“Round the next corner, where many theatrical and film stars live, several had slung hammocks on their meagre front lawns – one actually suspended between the bathroom windows of two adjacent houses. Midnight street wear for both sexes was cool if unconventional —silk pyjamas, bath robes, tennis shorts, and one in kilt and bathing costume top who could have gone straight into the arena at Lonach.”

The temperature at Westminster that night never fell below 23.3C (73.9 F), a record for July that still stands.

The column goes on to describe the situation in the House of Commons where the heat had reached “almost Turkish bath intensity”.

“Some members were in natty tussore silk suitings, but this helped little, and it was many of their number who appealed to the Speaker to have more windows opened. The Speaker, panting like the rest of us, said they were all open. If they wanted more cool breezes from the Thames, members would have to smash the windows.”

This hot spell and others features in my Premier League of Heatwaves.

29071948

synop.PNG

850.PNG

June 2019: record heat spike

June 2019 saw no high temperature records broken but a jump in anomaly, produced on the 29th by the 3rd hottest June day back to 1959, is higher than any I can find back to that year..

The only phenomena similar that I can find, albeit in the other direction, is the Beast from the East in March 2018 that sent temperatures plummeting.

The month finished a little above average though the final figure, like May and April, masked cool warm spells.

The mean temperature finished 16.9C that’s 0.8C above average, the coolest for 3 years.

Rainfall was 63mm, 123% of average, the wettest for 2 years. Sunshine was 158 hours, 88.7% of average, and dullest for 3 years.

A timelapse of the longest day can be found here.

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

june 2019
‘Feels like’ maxima.
12.1
June 1981-2019 maximum anomalies
june anoms

 

The 12 month rolling rainfall total, thanks to a wetter than average month, has moved above 500mm again.

Summary for June 2019

Temperature (°C):
Mean (1 minute)  16.8
Mean (min+max)   16.9
Mean Minimum     12.1
Mean Maximum     21.7
Minimum          7.1 day 08
Maximum          33.6 day 29
Highest Minimum  18.0 day 24
Lowest Maximum   14.4 day 10
Air frosts       0
Rainfall (mm):
Total for month  63.3
Wettest day      18.7 day 10
High rain rate   20.1 day 09
Rain days        13
Dry days         17
Wind (mph):
Highest Gust     24.4 day 08
Average Speed    2.7
Wind Run         1932.6 miles
Gale days        0
Pressure (mb):
Maximum          1031.5 day 27
Minimum          998.4 day 07
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        0.0

 

 

 

 

 

 

 

The coldest and wettest days of June

Looking out the window on a cold and miserable June afternoon yesterday reminded me of similar such days during the Seventies and Eighties.

But the mind plays tricks and I wondered if these kind of days were that common in the past.

To weed out the also-rans qualifying days had to be sunless with an anomaly that was at least 4C cooler than the daily average and rainfall of at least 12mm.

This gave the following list.

24hrd

So, in the last 60 years there have been only 12 days similar to June 10th 2019. That would give a probability of less than 1% (0.00743)

Looking elsewhere it would appear that there was much more rain to the north, south and west of Wanstead.

rain all

 

 

The curse of June 13th

1 Jun 21 Jun 16 Jun 77

June can be a strange month weatherwise. Scorching temperatures as well as washout, cold weather, perhaps epitomised by the Queen’s Diamond Jubilee pageant on the river Thames in 2012, can feature prominently.

The month can also throw up some striking anomalies, none more so than the fact that the 13th is the only day in the month where the temperature has ever reached or exceeded 30C anywhere in the British Isles.

According to TORRO the highest daily maximum recorded in the UK is 28.3C at Earls Colne, Essex, in 1948; at Brixton, south London, in 1896 and Aboyne in 1994. Yet either side of this date has records comfortably above 31C, as the table below shows.

torro.PNG

The closest we’ve got locally to 30C in the last 60 years was in 1989 when 27C was recorded.

So why is the 13th ‘cursed’ with traditionally being the coolest day of the month? The best explaination perhaps is the fact that the date occurs more or less during the middle of the North-west European monsoon.

According to Philip Eden’s list of singularities the June monsoon can strike any time between the 1st and 21st but normally peaks on the 16th with a 77 per cent frequency.

As well as cool temperatures the phenomenon can also bring copious amounts of rain, as happened in 1903 when large parts of Redbridge were inundated following a 59-hour deluge that started on… the 13th.

Will we see a repeat this Thursday? Unlikely, though the general pattern is not that different to what led to events over a hundred years ago.

13th

 

 

May 2019: average but dry

May finished average though the final figure, like April, masked cool warm spells.

The mean temperature finished 13.2C that’s 0.1C above average and nearly 2C cooler than last May.

Only 28.3mm of precipitation were recorded, 55.3 per cent of the 1981-2010 average.

Some 175.8 hours of sunshine were recorded, that’s 96.8 per cent of average..

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

may tmax.PNG
‘Feels like’ maxima.
may 2019 feels like.PNG
May 1981-2019 maximum anomalies
may since.PNG

 

The 12 month rolling rainfall total has fallen below 470mm for the first time since July 2017.

12 month.PNG

Summary for May 2019

Temperature (°C):
Mean (1 minute)  13.3
Mean (min+max)   13.2
Mean Minimum     8.1
Mean Maximum     18.4
Minimum          2.5 day 11
Maximum          25.3 day 23
Highest Minimum  16.0 day 25
Lowest Maximum   10.9 day 04
Air frosts       0
Rainfall (mm):
Total for month  28.3
Wettest day      7.3 day 07
High rain rate   52.3 day 26
Rain days        11
Dry days         20
Wind (mph):
Highest Gust     20.6 day 04
Average Speed    1.9
Wind Run         1637 miles
Gale days        0
Pressure (mb):
Maximum          1041.8 day 13
Minimum          991.6 day 08
Days with snow falling         0
Days with snow lying at 0900   0
Total hours of sunshine        0.0

Front loaded rainfall months

Since February most of this region’s rainfall has been falling during the first half of the month.

feb

February: 86%

march

March: 134%

april

April 28%

may

May (to 26th) 54%

With only one of these months wetter than average the long-term, rolling trend continues to head downwards.

rolling

Considering past rainfall patterns it can only be a matter of time before the graph heads upwards again. Looking further back at rainfall data to 1961 reveals the extremes were higher and that the jump from dry to wet can be sudden.

The wettest 12-month rolling period ended mid way through May 1975 with a total of 873mm. However, just 16 months later, at the end of the hot summer of 1976, the rolling 12-month average was just 302mm, that’s less than half of our average annual rainfall!

average rain

 

Meteorology-based musings about east London and beyond

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