
Britons sizzled in 31C temperatures today as a Spanish Plume swept in across the country with forecasters promising of similar conditions tomorrow before thunderstorms bring misery to the Bank Holiday weekend.

The Met Office said the mercury soared to 31C at Heathrow in London by 3.30pm and hit 30C at Gravesend in Kent as a 'blowtorch' of hot air swept in from north Africa and Spain.

Much of the rest of the country also enjoyed temperatures in the high 20s with thousands flocking to parks and beaches to make the most of the long-awaited heatwave.

Forecasters are now promising that temperatures will also soar towards 31C tomorrow - bringing another day of sunshine and cloudless skies.

It has prompted the Government to issue repeated warnings about the stifling heat - amid concerns for the welfare of the elderly, ill and children.

Despite the two-day spell of warmer weather, forecasters warn the conditions will deteriorate by Thursday when the warmer air mass combines with cooler air from the Atlantic, bringing thunderstorms and heavy rain.

It means Britons should be prepared for a 'washout' Bank Holiday weekend, which will also be marred by thousands of miles of traffic jams on the nation's roads as millions hope to make the most of it with a getaway.

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How inviting: Britons are sizzling in 30C temperatures today as a Spanish Plume sweeps across the country prompting the Government to issue a string of health warnings. Pictured: Archie Alder, Theo McAdam, Ruby Alder, Evita McAdam Dylan Pryce-Jones and Charlie Silsock jump into the pool as people enjoy the hot weather at Cheltenham's Sandford Parks Lido

Topping up those tans: Forecasters say the mercury will rise to 30C in much of the south east of England and London today including at Hampstead Heath Mixed Bathing Pond in north London where women were making the most of the sunshine

Feel that glow! Skye Cooper Barr and Aminah Ibrahim sunbathe at Hampstead Heath Mixed Bathing Pond in north London

Hello sunshine! Two women lap up the sun's rays as they relax alongside Hampstead Heath Ponds in London this afternoon

Here we go! Two young women jumped into the water at Hampstead Heath Ponds in a bid to cool down this afternoon

What wonderful weather: Hundreds of people flocked to Cheltenham's Sandford Parks Lido today to soak up the sunshine

Beware of the Bank Holiday weekend traffic jams: This graphic shows the delays expected on Britain's roads this weekend with the 11 'congestion hotspots' shown and the length of the delay expected (in brackets), according to travel experts

Experts predict that more than 20 million motorists are expected to take to Britain's motorways over the three-day Bank Holiday weekend – with lengthy tailbacks expected from Thursday right through until Monday.

Saturday is set to be by far the busiest day with five million getaways planned, while more than 4.5million drivers will take to the roads on Sunday. Friday evening is also expected to be jam-packed on the motorways.

Rod Dennis, from motoring group RAC, warned: 'Our study of drivers' plans for the late August bank holiday certainly suggests a bumper time on the roads as motorists make the most of the last long weekend before the end of the summer by jumping in the car to see friends of family.

'The see-saw weather patterns – warm, dry and sunny one day, cool, wet and windy the next – look set to continue but any doubts about the weather clearly are not playing on motorists' minds with so many of us planning a late August break.

'Drivers can expect some queues, especially on the busiest routes to the coasts, Lake District and major cities.

Taking a dip: Britons flocked to Bournemouth beach in Dorset to paddle in the shallows today as the country enjoyed 30C temperatures thanks to a 'blowtorch' of hot air from Spain which will bring a long-awaited two-day heatwave

Kick back and relax! A couple lap up the sun's rays in Hyde Park, London, today as temperatures in the capital soared

Working on her tan: One woman enjoyed the sunshine in London's Hyde Park this afternoon as the mercury rose to 30C

Don't overdo it! These ladies look like they are in danger of getting burnt in Mediterranean-style sun in Hyde Park

On yer bike! Two boys enjoyed cycling on bikes in London's Hyde Park this afternoon as temperatures soared to 31C

Cooling off! Regime Bagociute, six, plays in the fountains of Bradford's City Park this lunchtime as temperatures soar

Making the most of it: Britons enjoyed going out on the Serpentine Lake in Hyde Park this afternoon as the heatwave came

What a beautiful view: There was a stunning sight to be had from a bridge overlooking the Serpentine in Hyde Park today

'It can be a good idea to travel outside peak times. This Friday evening, plus through the day during Saturday and Sunday are likely to be the most hectic with bumper-to-bumper queues expected on some parts of the network, so motorists that start their journey early or much later on each day might be rewarded with a much clearer run on the roads.'

Ahead of the weekend, Britons are facing an intense heatwave before thunderstorms wash away the heat.

A Level Three heatwave alert is currently in place which warns hospitals to prepare to be busier than usual in eastern England today and tomorrow.

Caused by 'warm air pushing up from the continet', the alerts cover from 12pm on Tuesday - where temperatures hit 29.7C (85.5F) in St James Park and 30C in Gravesend, Kent - to 9am on Friday.

Sunny dreams: Two stylish young women soaked up the sunshine in Whitehall Gardens in Westminster, central London

Topping up that tan: One woman relaxed in St James's Park in central London this afternoon as the mercury hit 31C

One man took off his top as he tucked into honeydew melon in Whitehall Gardens in Westminster, central London, today

Relaxing with some music: One woman kicked back in a deckchair in St James Park in central London late this afternoon

Stunning: It was a beautiful day at Hatfield House, Hertfordshire, today as temperatures soared to 31C in the south east

Well that's one way to kick back! Two men enjoyed a quick game of table tennis in Whitehall Gardens in Westminster today

Picturesque: Sandsfoot Castle in Weymouth, Dorset, was surrounded by lush green grass and blue sea in the sun today

Cheers! This resourceful couple have brought their own fridge to a sunny riverbank in Caversham, near Reading, Berkshire

Doctors say hot weather is potentially lethal for the elderly, ill and babies, as their bodies suffer daytime heat stress. Public Health England warned: 'Excessive exposure to high temperatures can kill.'

Dr Thom Waite added: 'Now the heatwave has arrived, people will likely be out and about more enjoying the summer sun.

'That's why it's really important to remember that there are some people whose health suffers in hot weather.

'Older people, those with underlying health conditions and young children may all feel the ill-effects of heat over the coming days.

'We're urging everyone to keep an eye on those you know who may be at-risk this summer. If you're able, ask if your friends, family or neighbours need any help.'

Dr Waite said the hot weather can 'put extra strain on bodies' and urged people to 'stay hydrated' during the hot spell.

His tips to keep cool include closing curtains, keeping out of the sun between 11am to 3pm, wearing loose fitting cotton clothes and applying suncream.

FEELING HOT, HOT HOT! WHAT IS A SPANISH PLUME AND HOW DOES IT OCCUR? A Spanish Plume is a weather pattern in which warm air moves from the Iberian plateau or the Sahara to northwest Europe. It reaches the British Isles on a southerly airflow, which brings warmer weather as opposed to the much cooler Atlantic air we are used to. As the warm air meets cold fronts from the west, the 'plume' air is forced to rise vigorously over the Atlantic air and as a result produces thunderstorms. The storms can can give widespread heavy rainfall, often accompanied by hail. Advertisement

Soaking up the summer sun: People were relaxing in Mill Meadows in Henley-on-Thames in Oxfordshire this afternoon

Perfect day for a picnic: People were enjoying the sunshine at Mill Meadows in Henley-on-Thames in Oxfordshire today

Ice-creams this way! Londoners enjoyed a frozen yoghurt on Southbank in the capital as the mercury soared towards 30C

Grabbing five in the sun: Workers enjoyed a spot of relaxation on London's Southbank at lunchtime as the sun beat down

Forever blowing bubbles: Children enjoyed a bubble-maker on London's Southbank as the temperature soared to 30C

Lunch in the sun: Londoner's in the Southbank and Waterloo area enjoyed their break in the sunshine as the mercury rose

Sailing in the sunshine: A man and a woman enjoyed cruising along the River Thames at Henley in Oxfordshire today

Met Office forecaster Grahame Madge also warned people to take care in the heat. He said: 'People who suffer in the heat need to take account of temperatures in the next few days.

'33.5C is the highest temperature this year, and we could get close.

'The warmest conditions are likely to be across central/west England as well as London and northern parts of south east England.'

One thousand more Brits than average died in July's heatwave, when temperatures peaked at 33.5C on July 19.

A total of 574 deaths above the average were recorded in the week ending July 22, with a further 623 above-average deaths in the week ending July 29, Office of National Statistics figures for England and Wales show.

Gently down the stream: A father and child enjoyed a boating trip down the River Thames in Henley, Oxfordshire, today

Scenic: Hundreds of people flocked to Mill Meadows at Henley-on-Thames, Oxon, this afternoon to lap up the sunshine

Park life: Londoners are enjoying the sunshine at parks across the country including at this one near Southbank today

Catching up: One woman checked her phone while laying in the bright sunshine at Mill Meadows in Henley this afternoon

Hot! Londoners enjoy the warm weather in Hyde Park, Central London, today as the country enjoys soaring temperatures

Row, row, row your boat: A trio head out onto the Serpentine in central London on a small boat as a couple watch on

Britain at its best: Canoeists paddle along the River Thames at Sonning-on-Thames in Berkshire in sunshine this afternoon

Feeling the heat: Sunseekers descended on Bournemouth beach today to make the most of the sizzling conditions today

This Met Office graphic shows where temperatures are expected to soar across Britain today thanks to the Spanish Plume

Feeling hot, hot, hot! This Met Desk graphic shows where the warmest parts of Britain will be today (shown in red above)

CAR JOURNEYS BY DAY The number of motorists expected to take to Britain's roads over the Bank Holiday weekend: Thursday - 3.1 million Friday - 4.1 million Saturday - 5 million Sunday - 4.4 million Monday - 4.1 million Advertisement

The ONS said deaths are often reported several days after occurring.

After two days of intense heat, forecasters warn the warm weather will be replaced by thunderstorms by Thursday.

Temperatures are likely to fall to around 25C by the weekend, as thunder and lightning threatens the South.

A Met Office spokesman said: 'Thundery showers will arrive for some on Thursday. Friday will be drier, and Friday and Saturday have an outside chance of 30C but the mid-20s are more likely.

'Saturday will be generally dry, though showers are possible across central and southern parts with a risk of thunder, with Sunday seeing cloud and rain pushing across northwestern parts and thunderstorms possible in the far South-East. Thereafter, a more a changeable pattern is likely.'

Picturesque: The magnificent Sea Cloud II sailing cruise ship rolls into Dartmouth, Devon on this beautiful sunny morning

What a start to the day! A bright rainbow in the clouds appeared over Cow and Calf Rocks on Ilkley Moor, Yorkshire today

Beautiful scenery: Forecasters say the mercury will rise up to 30C in much of the south east today with some parts even fetching up to 33C as a 'blowtorch' of hot air sweeps in from north Africa and Spain. Pictured: Corfe Castle in Dorset today

Here comes the sun: A misty but colourful start to the day at Eridge Park, East Sussex ahead of the long-awaited heatwave

What a difference a day makes! Yesterday (left) this stretch of beach in Looe, Cornwall was virtually empty under cool, overcast skies. But today (right) the sun was out and people were more worried about sunburn than rain