Summer 2024 will go down as a disappointment for Northwest Europe and hottest on record for Southeast Europe and for that matter, most of the continent east of Germany.

While the west of the continent observed fluctuation as the season progressed (trough replaced by ridge), the east remained on the hot side throughout.

Summer got off to a slow, cool and wet start for ALL of Western Europe but as the season progressed, heights climbed over Iberia providing a much warmer 2nd half to summer with frequent hot spells extending from Africa to France and at times the southern UK. It was a much improved 2nd half to summer for southern UK.

Two key high pressure cells dominated the season, 1 over the west-central North Atlantic and 2nd east, southeast Europe with trough in between. Despite fluctuation in intensity of both ridge and trough, this standing wave pattern remained very persistent through much of the summer.

For NW Europe, the trough and storm track started off far to the south in May and June reaching the Azores and Iberia. Disturbances even made it down to the Canaries at times.

As the season progressed, the trough, storm track and rainfall all retreated northwards allowing heat to build further west. Essentially as a very wavy upper pattern gave way to an increasingly flat and strengthening zonal flow. WNW winds in the first half (June-mid July) gave way to WSW winds during the second half (mid July-August) in the means.

While cool WNW winds dominated much of June through the first half of July from Scotland to Spain, there was TWO heat surges, both of which came during the 2nd halves of both June and July. The 1st arguably Scotland and Northern Ireland’s ‘only’ visit of appreciable warmth but periodic visits of 30C days came to southeast England.

June was dry for UK (except NW Scotland), wet for Iberia and France but into July it turned wetter across southern and central UK (a small trough core developed WSW of Ireland which focused frequent bouts of heavy rain into southern and central UK). Change came mid July as heights rose over Iberia and that trough WSW of Ireland dissipated with pressure building from south but consequently lowering over Iceland. This changed the shape of the pattern.

August saw the storm track move to it’s most northerly position but strengthened as the thermal gradient between eastern North America as well as Greenland and subtropical Atlantic increased.

Note strong warmth at 500mb (18,000ft) positioned well to the north over the eastern Atlantic from subtropics to mid-latitudes and UK and deep trough just south of Iceland.

This warmth meeting an increasingly cold air mass over Greenland drove a stronger than average 925mb or 2,500ft level winds seen in the 2nd graphic below.

The stronger than average low level to upper level winds have created a notable west-east cooling but with considerable warmth underneath.

Another factor worth considering is the persistent sinking over the Atlantic, perhaps aiding a lot of warmth within the tropical and subtropical Atlantic from surface to upper levels.

Rainfall while fairly sparse during the first half of summer, really increased in August over Western Scotland and Iceland as the jet lifted north.

As the ridge shifted west over southern Europe, so the Icelandic low deepened. While a reasonably warm August in SSE UK, it’s been a cool, wet and often windy August in N and particularly NW UK, so much so it’s been parts of Western Scotland’s wettest August, even summer as a whole.

Summer 2024 in maps

500mb geopotential height anomaly for June.

June temp anomaly.

500mb geopotential height anomaly for July.

July temp anomaly.

500mb geopotential height anomaly through 26th August.

August through 30th temp anomaly

August 2024 Monthly Weather Report

UK Met Office August Highlights

Highest Maximum 34.8°C on 12th at Cambridge, Niab (Cambridgeshire, 26mAMSL)
Lowest Maximum 12.0°C on 25th at Dalwhinnie No 2 (Inverness-shire, 351mAMSL)
Highest Minimum 20.9°C on 12th at Gogerddan (Dyfed, 31mAMSL) and Yeovilton (Somerset,
20mAMSL) and Gosport, Fleetlands (Hampshire, 1mAMSL)
Lowest Minimum -1.2°C on 31st at Kinbrace, Hatchery (Sutherland, 103mAMSL)
Lowest Grass
Minimum -2.5°C on 31st at Dalwhinnie No 2 (Inverness-shire, 351mAMSL)
Most Rainfall 154.4mm on 21st at Honister Pass (Cumbria, 358mAMSL)
Most Sunshine 14.2hr on 10th at Cawood (North Yorkshire, 6mAMSL)
Highest Gust 64Kt 74mph on 22nd at Capel Curig No 3 (Gwynedd, 216mAMSL)
Highest Gust
(mountain*) 86Kt 99mph on 10th at Cairngorm Summit (Inverness-shire, 1237mAMSL)
Greatest Snow
Depth at 0900
UTC
No non-zero values.

According to SEPA, Allt Dearg House on the Isle of Skye recorded a record-breaking 719.4mm of rain during August alone.

My August Stats

Summer overall

500mb geopotential anomaly for 1st June through 26th August.

Temp anomaly for June through August.

MET OFFICE: UK experiences coolest summer since 2015

Soggy end to Scottish summer as some areas record wettest August on record

Like for the UK, it’s been a contrasting west vs east divide in rainfall across Europe this summer with constant heat and sunshine in the east and southeast of the continent while a very different story for northwest Europe. Coolest for 9 years in the UK, hottest on record in the Balkans and the below drought maps show this and how the summer has progressed between May and August.

End of May

End of August

August Highlights

Final morning of August saw big UK temperature contrasts. Kinbrace in Scotland fell to -1.2 °C, whilst Manston in Kent held up at 16.6 °C

Tweet from London & Southeast

Summer 2024 will finish with 4 days with ≥30C Tmax in London, this is below the recent decadal average. While it is not as much below as 2023 summer with 2 days. However, last year had an exceptional September to pick up shortcomings we picked up 7 in succession totally unprecedented! Only summer of 1976 had more consecutively. Up until 30 years ago, it was rather common for a year to pass without 30C in capital. In the 1960s and 1970s likewise, half of summers failed to reach 30C. The last summer to fail to see 30C in capital was in 2008 now over 16 years ago. Seemingly it grows increasingly more distant has it gone extinct?

 

Forecast vs Reality

Forecast

Reality

What was said…

From World Climate Service

MarkVoganWeather…

Actual

Combining what was said month-by-month and my synoptic idea, I would say it’s been a good summer prediction but being cooler, not warmer knocks down the score overall.

7.5 out of 10?

 

What’s September got in store?

Starting off with high pressure then return to lower pressure forced south? Looking hot for much of mainland Europe but possibly turning cooler, wetter in Iberia up through France.

What happens in the tropics could be significant. After all, in August, Debby indirectly aided the strongest heat surge of summer for the UK then Ernesto helped reinforce a trough and spell which produced a named storm in it’s wake. (12th of season and most in a year since naming started in 2015).

Autumn starts off with a 1028 high parked directly over the UK then retreats up into Scandinavia as a front slides into Ireland and UK. A brief surge of heat and humidity from the south will allow thunderstorms to moves into southern UK from France but also lift temps towards 30C with cloud breaks.

Pressures lower through the first few days of the month before likely rising once again from the north. This likely sets the tone for the first half of September with high to the north, low to the south with possible WNW shift in the high week 2 as seen in the below CFSv2 weekly.

Looks like a cut off low dives south between Azores and Iberia or Bay of Biscay, trapped beneath high pressure, this will threaten wet weather lifting north towards the UK.

CFSv2 weeklies

HP looks to become anchored somewhere N or NW of the UK in the means with variability which in turn determines source of air (warm or cool).

Note the total accumulated rainfall through first 10 days of Sept seen by the GFS. Fits the wetter south, drier north narrative.

September as a whole seen by the models.

GFS ext

ECM weeklies

For UK & Ireland, I expect September to be quite variable with a mix of warm and cool episodes and potential for a ‘cold spell’ mid to late month. Overall around average for temperature. Drier in North, wetter in South but wet conditions could spread further north… Warmer than average for much of Europe!

THIS ARTICLE WILL BE COMPLETED WHEN AUGUST DATA COMES IN…

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