It’s been another hot day across the southern half of the British Isles, a phrase I rarely use but it pops up a couple of times a year when the temperature surpasses 30C (86F). Though we await the official high from the Met Office, the temperature has topped at least 31C (88F) today around London making this the warmest day of the year across the UK, passing the 30.1C recorded just yesterday at St James Park, London.

Even up here across Scotland this afternoon temperatures rose to a very pleasant 21C or 70 with decent spells of hazy sunshine.

Another warm night for all, especially over London. Suttle changes kick in tomorrow with east breeze, cloud increase

Like last night, tonight will be another mild, misty, foggy but calm night across the board and a warm, muggy one throughout the Southeast following a warm day, Temperatures will once again be slow to cool within the heat retaining environment of London. Tomorrow looks to be another very warm one with highs comparable to the past couple but there are suttle changes in the forecast. While you’ll have noticed a humidity increase today, an east breeze will kick in, allowing London to see a degree or two drop in temperature from today. So perhaps 29 or 30C compared to 31-32C today, yes it’s a very slight change but this is a sign of bigger changes looming for Friday, the day millions across the world have been waiting for. Clouds will also increase tomorrow and a few showers may pop over the Midlands, maybe an odd one over the south, southeast.

Highs should make 80F again on Friday but showers and thunderstorms are expected over London between 4-6pm, should clear in time for Olympic opening ceremony at 9pm

Thursday night into Friday will once again be another mild one which sets the stage for another day in the 80s F for London, though a further 1-2C gets knocked off Thursday’s 29-30C, it will still be very warm and well above the seasonal average of 23C (73F). Clouds increase  further and earlier than what we’ll see tomorrow and this is the sign of a cooling of the mid and upper levels as the trough begins it’s journey down across the British Isles, setting the stage for the weekend.

By the time we reach noon Friday I believe showers and thunderstorms will begin to bubble up over the Midlands and the South, including London. The temperature does look to push 27 or 28C (80-81F) again but it depends upon when those showers develop. The front will slide north to south over London sometime between 4-6pm and this is when the greatest chance of showers and thunderstorms will be. This is not only right in the heart of the Friday evening rush hour but at a time when thousands ascend upon the city for the Olympic opening ceremony.

Any showers and storms which pop ‘should’ and I must highlight that word ‘should’, clear by the time 9pm comes, giving way to a very pleasant, cooler evening with a much more refreshing air flow coming down from the north on the backside of the front.

Saturday sees rain spread down over Scotland into northern England with temps back in the low 60s, London only warms into the low to mid-70s, only 60s by Sunday or Monday

By Saturday, low pressure will be back in control with greatly reduced heights, especially further north with rain spreading southwards over Scotland northern England, NI and the Republic. With all the cloudcover, rain and breeze, it will be quite a raw day with highs in the north of Scotland perhaps struggling to 13 or 14C while the Scottish Central Belt and the rest only rise to between 14-17C (54-63F) Nights could get chilly in this region, especially under clear skies within night mins between 4-8C (40-47F), even chillier in rural areas. With sunshine but much fresher air over London and the South, temperatures will still rise to around average or slightly above at between 22-23C (72-73F), depending upon amount of sunshine. You’ll notice much more comfortable nights down at around 10-12C (50-52F).

Either Sunday, if not certainly Monday, it looks like London bottoms out with highs failing to reach 21C (70F) so quite the turnaround from today through Friday.

Interestingly, the ECMWF shows the low initially pushing NW, then W, then finally SW by mid next week. This would allow SW winds to draw warmer air back up into the UK with potential fo0r highs returning to the 25-27C range from Wednesday through next weekend. Saty tuned and lets see if the models holds to this idea!

Tags: london 2012 weather, london weather, olympic forecast, uk weather