Quick! If you’re reading this indoors, get yourself outside sharpish.
You need to soak up the glorious spring sunshine while you can – because by tomorrow it’ll be on its way out.
And unless you plan to cook kebabs in your coat, forget those plans for a weekend barbecue.
Once we get to Saturday the weather will have reverted to damp and chilly.
Beautiful spring day: Student Chloe Kirkpatrick, 20, enjoys the warm weather in the Isabella Plantation in Richmond Park
Lunch outside: City workers relax in the sunshine in London yesterday as temperatures rose to 21C. Although it was warm in the south, the weather was far more overcast in many areas
Park life: A group of people enjoy a picnic in the warm weather in Regent's Park today as temperatures hit 21.1C
Today is set to be the warmest day of what, for the South at least, has been a week of warm sunshine. The mercury could reach up to 22C (72F) in some parts of the South, although it will remain considerably cooler in the North.
But tomorrow even the hardiest of souls would struggle to sunbathe, with temperatures set to plunge to 13C (55F).
And by Saturday a band of damp and mild weather will cover much of the country, making it a far chillier 11C (52F). Although temperatures are expected to recover early next week, forecasters say the unsettled conditions will remain until after the early May bank holiday weekend, when warmer air is set to sweep in from the East.
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At last, it feels like summer! England celebrates the sunshine (oh, and St George's Day) in temperatures of 20C
Met Office forecaster Charlie Powell said: ‘If you are lucky enough to get out today, then you should enjoy the warm weather, as it’s set to become much milder over the weekend.
‘People in the South and South East have been particularly spoilt in the last few days, with sunny and dry conditions, so the change in temperatures and return of showers will be noticeable.
‘But although the weekend will be a bit of a mixed bag and closer to the seasonal average, it will still be pleasant enough for many.’
Warm: Lunch time for city workers in London yesterday as they made the most of some unseasonably warm weather
There will be sunshine along with the showers, and temperatures will edge up to 14C (57F) on Sunday.
With the weather remaining topsy-turvy, the odds of snow falling in any British city in the first May bank holiday have been slashed from 10/1 to 2/1.
Sunseekers flocked to open spaces in the south yesterday as temperatures soared to an unseasonably warm 21C - after weeks of chilly weather.
But there was be a real north-south weather divide with rain across the Midlands and temperatures as low as 10C in Scotland.
Forecasters had predicted yesterday could have been the warmest day of the year so far and break through the 22C barrier.
Warm weather: A woman, left, eats her lunch on the steps of St Paul's Cathedral yesterday while Alice Aungier, a student from Essex,right, enjoys the sun at Southend Beach
Walking in a spring wonderland: A group of three people stroll through Sefton Park, Liverpool, yesterday among the daffodils
Spring day: A lady sits on a bench in Sefton Park, Liverpool during the warm spring weather
The warm weather comes as a welcome relief after the coldest March for 51 years - when it averaged just 2.5C.
The mercury reached 21.1C (70F) at 3pm yesterday in Cavendish, Suffolk, as the South East and East Anglia enjoyed conditions pushing up towards the best so far this year.
Elsewhere it was cooler, with overcast conditions in central and northern England and some rain in places.
Gareth Harvey, a senior forecaster with MeteoGroup, said: 'There's been quite a lot of cloud but it's not been like that everywhere - there have been local pockets of brightness.
'In areas that have been warm today, it is expected to be similar tomorrow, and we should see readings of 20C or 21C again, with sunshine across the south-east quarter of the UK.
Mild: A group of people enjoy the warm spring weather in central London yesterday
Stroll in the park: A woman walks through Regent's Park yesterday as temperatures soared to 21C
Sun seeker: A man relaxes A man relaxes on the beach in Herne Bay, Kent, as the warm weather continued yesterday
'It is likely to be cloudy again elsewhere, and as we move towards the weekend we can expect to see it turning chillier, with temperatures in East Anglia down to 10 or 12C by Friday - quite a large drop.
'Much further north there could even be some wintry showers, as conditions remain unsettled over the weekend.'
Temperatures are expected to start recovering on Monday and Tuesday, with the mercury gradually rising through the week.
Meanwhile, hay fever sufferers have had some good news after 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.
Beverley Adams-Groom, pollen forecaster at the National Pollen and Aerobiology Research Unit, said: 'The most important tree pollen type is silver birch which triggers hay fever in approximately 25 per cent of sufferers.
'The cold weather of the last few months will delay the release of birch pollen which, in an average year, starts to be emitted from around the beginning of April in the south of the country. This year it could be at least two weeks later.'
Ms Adams-Groom added: 'Grass pollen affects around 95 per cent of hay fever sufferers in the UK.
Spring blooms: Another group of people enjoy the warm weather in a central London park. Unfortunately the good weather will be gone by the weekend
Great outdoors: Office workers near St Paul's Cathedral in central London enjoy the weather on what forecasters said could have been the hottest day of the year so far
Warm spring weather: Mangolia trees finally flower in Stoke Park, Slough, on what was one of the warmest days of the year so far
Britain in bloom: Magnolia trees that have flowered in Stoke Park, Slough. Temperatures could rise as high as 22C in the south-east today
Contrast: In spring 2012 this field near Wantage, Oxfordshire, left, was a sea of spectacular scenery as rape seed blossomed. However, after a dismal start to 2013 (right) it is looking a lot less colourful. The field is by no means alone in demonstrating the effects the cold snap has had on British wildlife this spring.
Bird watchers have also been reporting a huge drop in the number of seasonal Chiffchaffs and Sand Martins that usually grace British skies at this time of year.
Data held by the British Trust for Ornithology shows a drop of 30 per cent in reported sightings of Chiffchaffs.
Warm weather: After a cloudy start for many today (left) it could reach as high as 22C today, and similar again tomorrow. But on Friday it will be cooler with rain across the country
'There are a number of grass species that flower ahead of the main pollen season, often in April, such as sweet vernal grass and foxtail. The cold weather will delay the flowering of these types which is good news for those people who are affected by these species. However, it's too early to predict what will happen during the main grass pollen season.'
On Tuesday, in Bournemouth, Dorset, many of the 3,500 deckchairs on the seafront had been taken up as people flocked to the coast.
Families, students and officers workers on their lunch breaks were all soaking up the sunshine.
Debbie Brown, 35, from Poole, was walking along the promenade with her children Max, four, and Charlie, two.
She said: 'Finally we have a spring! We've had such miserable weather for what feels like forever so when I heard the forecast this morning I almost couldn't believe it.
'I thought it best to make the most of it as it will probably turn cold again knowing this country.
'The kids have enjoyed a nice time building sandcastles, it's such a far cry from a few weeks ago when we were stuck inside with all the rain.'
Bright start: The sun streams through trees today as a man takes hid dog for an early morning walk in Micheldever Wood, Hampshire
Beautiful rainbow: Alan Heighway, 66, from Telford took this spectacular picture on Sunday when he was caught in a rain shower. Remarkably, the rainbow formed a perfect arch over the houses of West Street in Telford