This weekend: summer heat returns, but will it last?
There’s no denying that in comparison to the past few summers, this year hasn’t been that great, with days of warmth and sunshine coming in short bursts, rather than anything long-lasting.
August has been particularly poor, with much of the country, but especially Scotland and Northern Ireland, seeing cloud, wind and rain that wouldn’t look out of place in early autumn.
However, as I wrote in a recent blog, August isn’t renowned for delivering good weather. Seven Augusts in the last decade have been wetter than normal.
In fact, four of them have been significantly wet – 2008, 2009, 2012 and 2014 had rainfall 49, 29, 24 and 55 per cent above normal respectively.
Summer heat returns for some this weekend
Saturday will see hot and humid air spread up from the south across much of England and the far east of Wales. But as has been the case for much of this summer, it’s not going to stick around.
Nevertheless, central and eastern parts of England, along with the far east of Wales, will have a hot and humid day on Saturday, with temperatures reaching 25-30C.
Don’t expect clear blue skies all day though, because cloud is likely to build through the afternoon and evening, with some scattered thunderstorms breaking out.
Whilst the chance of any one location catching a thunderstorm is low, if you do catch one, there’ll be torrential rain, lightning, hail and gusty winds, giving a risk of localised flooding.
The rest of the UK further north and west will be in cooler and fresher air, with temperatures closer to 17-22C.
This is because a weather front will stretch from south west England, up through west Wales, north west England and into south east Scotland.
It is this weather front that marks the dividing line between the hot, humid air and cooler, fresher air that will sit across Northern Ireland and most of Scotland.
In the meteorological world, weather fronts mark the boundary between air of different temperatures and humidity. The bigger the contrast, the more active the weather front and therefore the heavier the rain.
As the hot, humid air mixes with the cooler, fresher air, rain will become heavier and more widespread across western parts of the UK later on Saturday, before pivoting to affect other parts of the UK during Sunday.
An uncertain forecast
It is worth noting that there is a lot of uncertainty about precisely where the heavy rain will be and how it will pivot into Sunday, meaning that there is the potential for the forecast to go wrong.
That doesn’t sound helpful, but there are still a few weather situations where the weather computer models struggle to get the detail right.
Nevertheless, Sunday is generally going to be cloudier, wetter and not as warm as Saturday.