After the hottest London Marathon on record, Britain's heatwave is officially over and temperatures are set to plummet, possibly bringing snow to parts of the UK.
Following a weekend of sunshine and unusually high temperatures, with wintry weather is returning to some areas yet again, and showers on the way.
"Towards the end of the week it is certainly possible that the cold weather will include hail, sleet showers and snow, especially on higher ground," said Met Office meteorologist John West.
"The areas most at risk are the Lake District, North Pennines and Scottish Highlands, but we are not expecting a big impact."
Forecasters are predicting average temperatures of around 12 to 14C for much of the week ahead, with "no high numbers" of the kind enjoyed by much of the UK in recent days.
"The UK today is generally dry across much of England and Wales with bright or sunny spells but will generally be cloudier than it has been of late," said Greg Dewhurst, meteorologist at the Met Office.
"The north of England, Scotland and Northern Ireland may see outbreaks of rain as the day goes on."
"Som e of the shower s could be wintry across high grounds in Scotl and from late Tuesday into W ednesday."
Overnight, temperatures are expected to drop to around 9C or 10C, with a minimum of 3C in Scotland.
Patchy rain is set to continue throughout the week.
The cooler weather follows the hottest London Marathon to date, with temperatures exceeding 24C around St James’s Park yesterday, according to the Met Office.
A number of runners collapsed during yesterday's 26.2mile race, with the heat feeling even more extreme along the tarmac routes.
Competitors planning to run in fancy dress were urged to think twice by organisers, but many still donned outfits including Paddington Bear, a dinosaur, a lung and Forrest Gump.
A group of firefighters who attended the Grenfell Tower disaster took part in the race in full fire-fighting gear weighing around 30kg, to raise money for victims of the tragedy.
Now the heat is over, forecasters say we might have to wait till mid-May for the warm weather to return, when things should become "drier and brighter".
For the rest of the month, the outlook is a mix of rain and sunny spells, which forecasters say is "pretty normal" for the time of year,
Hay fever sufferers have been warned that the pollen count is high across southern England and Wales today, as well as on Wednesday and Thursday.
"We are in the tree pollen season," Mr Dewhurst said.
"Only 25 per cent of hay fever sufferers are affected by tree pollen. Grass pollen season does not start till May or June."
Additional reporting by agencies.
