Met Office spokesman Dan Williams confirmed that the two hottest temperatures of 22C were recorded at Manston and Gravesend (both Kent) on the 14 April, and it was the first time we've seen 20C+ in the UK since last September (17 September 2012).
Leon Brown, meteorologist at The Weather Channel, told Aol Travel we were more likely to be seeing highs of 21C - before temperatures start to drop again from Friday.
He said: "Yesterday, Saint George's Day, was the warmest day of the year for many locations in central and western England, reaching 19C to 20C, with Pershore 20.3C. The south east was warmest reaching 21.3C at East Malling but not quite beating the 22.1C recorded in Gravesend on Sunday 14 April.
"Today (Wednesday) and Thursday will again be warm in the south, and we could see 21C again in the London area, but by Friday prepare for a 10C drop in temperatures.
"Feeling a lot cooler from Friday and over the weekend. Gardeners beware of frost on Saturday night with temperatures as low as -2C at dawn on Sunday in rural parts of mid Wales and across the Midlands.
"Next week may be even colder still with temperatures struggling to reach 8C in the south east and East Anglia by Wednesday and Thursday with a biting north east wind and rain. So from T-shirts back to jumpers, coats and umbrellas!
"All this as a result of the jet stream taking a big southerly detour over the north east Atlantic and western Europe!
"This cooler weather looks set to continue to the early part of May, too, but we are hopeful that a large area of high pressure will begin building for the Bank Holiday on 6 May to bring settled and nearer normal temperatures again. The jet stream moving back to a more northerly track for a while, at least."
Phew! It's not all bad news, then...
Make the most of the sun at these top UK beaches:
The UK's ten best beaches (according to Tripadvisor)
Could Britain see the hottest day of the year this week?
The good: "Great beach with sand dunes for shelter from the wind and a lovely gentle slope into the water. Nice clean beach."
The bad: "Not really a beach for sunbathing or swimming, but a beautiful place for a walk. Well worth a visit."
Did you know? Oscar-winning actress Tilda Swinton lives in Nairn.
The good: "One of the 10,0000 wonders of the world" raves one Tripadvisor reviewer, while another calls it a "sandcastle makers heaven!" The bad: "What's all the fuss about? 60's apartments and tacky seaside galore." Did you know? Property here is notoriously pricey. In 2009 a 1,393-square-metre plot was reported to have been put up for sale for £13.5 million. Some houses going for a steal at £7,750,000!
The good: "Just watch the waves all day. Sunny but very windy day which is the best way to see Fistral Beach. Can spend hours walking around the headland then sit and have a drink whilst watching the surfers." The bad: "Parking restrictions a nightmare." Did you know? The British Surfing Association, Newquay Surf Life Saving Club and the Newquay Boardriders Club are all based at Fistral Beach and the Boardmasters Festival is also held there.
The good: "It's got sand, and clean sea. Enough said really." The bad: "All the above reviews are fine - that is if you can find somewhere to sit squashed in among the hoardes." Did you know? Weymouth was given a Royal seal of approval by King George III. He used to visit during times of illness for a restorative paddle.
The good: "My 'Safe Place'. I must have walked this beach over a hundred times in all weathers and it never fails to amaze me." The bad: "Why does everywhere you go for a pleasant walk have to be infested with dogs and their stupid owners?" Did you know: Longsands has its own webcam, so you can check out the weather before you head for the beach, see it here.
The good: "Beautiful beach surrounded by cliffs, large enough to never feel crowded even in peak season. A lovely beach bar on the beach which serves food all day and dog and child friendly."
The bad: "Perranporth Beach is lovely, what a pity about some dog owners who seem to think it is alright to allow their dogs to mess on the beach and then just walk away leaving it where young children are playing."
Did you know? The Perranporth Surf Life Saving Club is one of the oldest in the country and hosts an extreme triathlon event every autumn.
The good: "Hengistbury Head is one of my favourite places in the world. It's one of those spots that restores peace to your mind." The bad: "A bit bleak and windy, not much to do except pitch and putt." Did you know? People have been settling at Hegistbury Head since the Stone Age and it has over a million visitors per year.
The good: "Sun, Sea and a secret seal that visits the shore here most days. Family-friendly with lots locally to see and do - like dipping your toes back into 1960's seaside family holidays for the day." The bad: "Great beach but there are so many more spectacular and less populated beaches in the St Ives area." Did you know? It's home to the Porthminter Cafe, a multi-award winning seafood restaurant smack bang on the shoreline.
The good: "Heaven. The nicest beach I've seen in the UK." The bad: "Get your binoculars out...the sea is over there. The tide was out but there was a disproportionate amount of dry/wet sand (as in miles of wet and a small patch of dry) considering how far out the sea was." Woolacombe trivia: During the Second World War, the U.S. Army based their Assault Training Centre here. Thousands of small boat crews and infantry practised amphibious landing assaults on the beach because its long flat shape was considered to be like the Omaha Beach landing area.
The good: A "gem in the crown of Gower" has "unbelievable views"; it's "clean and peaceful... "The BEST in the West."... "The most amazing sight on the lovely Gower Coast."
The bad: "It is a lovely beach, but it is more of an adult orientated one, you park your car up the top of the hill and start walking, either down to the beach, or over the cliffs, which if you have children, I would not recommend."
Did you know? Rhossili Bay is located in an area designated as the first Area of Outstanding Beauty in the UK.