London: Parts of the UK could experience the warmest April day in almost 70 years with temperatures in the hottest spots possibly reaching 28C.

The current balmy spell is set to peak in the south-east of England on Thursday, where it is forecast to be hotter than Spain and Italy.

Temperatures are predicted to beat Wednesday’s highs of 25C in both Gravesend in Kent and St James’s Park in London — the warmest day of the year so far.

Sunny skies will push temperatures to the low 20s in most of England and Wales, but in the south-east thermometers are expected to hit 26C, 27C or 28C. While they are not expected to challenge UK’s the warmest April day of 29.4C recorded in 1949, they could beat the 2001 April high of 27.8C.

The heatwave comes just after over a month after the UK was struggling with snow and ice from the “beasts from the east”, which prolonged the winter well into March.

Five weeks later summer has come unusually early. Conditions will be mild across the UK, with Northern Ireland likely to push 19C in some parts and a peak of 20C possible in Aberdeenshire in Scotland, the forecaster said.

The hot weather far surpasses the average maximum temperature for April, which sits at 11.4C.

The summery spell is caused by warm air from the Azores being dragged up towards the UK due to area of low pressure over the Atlantic and high pressure over western Europe.

Meteorologist Alex Burkill said: “There’s a fairly good chance of 28C, there’s about a 60 per cent chance. Quite widely we are going to see low 20s, and for many it will be a little warmer than Wednesday.”

Thursday is expected to be the hottest day of the warm spell, with weekend temperatures dipping slightly before showery outbreaks on Sunday.

Competitors in the London Marathon could expect hot and humid conditions with a forecast of between 21C and 23C, Burkill said.

“There could be a shower but it’s not very likely. It’s not great conditions for running. In fact if any showers do come they might be very welcome,” he said.

Some hay fever sufferers could be affected by high pollen counts, he added, saying: “For anyone who suffers from tree pollen they will probably be feeling the effects, but that’s only about 20 per cent of hay fever sufferers. Grass pollen season comes later in summer.”