Weather: Britain Set For Hottest Day Of Year

Spring sunshine has seen parts of the UK enjoy the hottest weather of the year so far - before plummeting temperatures and a sudden cold snap take hold.

Large swathes of east Wales and southern and eastern England have been basking in clear skies and bright sunshine, with 21.1C (70F) recorded today at Cavendish in Suffolk.

Elsewhere it was cooler, with overcast conditions in central and northern England and some rain in places.

While temperatures will plunge by Friday, Wednesday has been the warmest day yet of 2013.

Sky News Weather Producer Joanna Robinson said: "Southeast England looks to keep the warmth over the next few days, but there will be more in the way of cloud around than on Tuesday.

"Temperatures could reach 21C (69.8F) or 22C (71.6F) in the best of the sunny spells there, which would equal the highest temperature we've seen so far in 2013, in Manston and Gravesend on April 14."

But she added that the mercury could drop below double figures in many parts of the country later in the week.

"Unfortunately, it doesn't look like the warmth will last into the weekend," she said.

"Rain will spread across south-east England on Thursday night, allowing the cooler air further north to set in.

"Friday and Saturday look to be fairly cold nationwide, with temperatures reaching a high of just 10C (50F) or 11C (51F) in the South East.

"Scotland and Northern Ireland will see temperatures around 8C (46.4F). It will feel even colder in the northerly wind and we'll also see the return of overnight frosts too.

"Spring is a changeable season so it's not unusual to see spells of warmth along with cold snaps."

Meanwhile, hay fever sufferers have received some good news as experts predicted a shorter hay fever season this summer.

Cold weather over recent months is thought to have delayed the release of silver birch and grass pollen.