A heatwave has been declared after temperatures reached 28C in parts of Britain for a third consecutive day.The Met Office said the criteria for a heatwave was met at Heathrow today when the mercury soared to 30C by 2pm.Southern England and the Midlands could reach a balmy 32C today, according to forecasts, with there being a 20 per cent chance of 34C. And it could be just as hot tomorrow when it is predicted to be a sizzling 34C, breaking the record for the hottest day in May and for a bank holiday. The record currently stands at 32.8C in the UK and England, and 30.6C in Wales. The UK and England's hottest bank holiday sits, for now, at 33.3C.Britain yesterday saw the hottest day of the year when the village of Frittenden, in Kent, hit 30.5C.It was the first time this year that the UK had passed 30C. The last time that happened in May was in 2012. But temperatures are expected to rise further today to a baking 31C in the South East. There is a chance of a 'tropical night' - the first time this has happened in May - at the end of the bank holiday, where temperatures do not drop below 20C. Amber heat health alerts were issued by the UK Health Security Agency on Friday morning for the East Midlands, West Midlands, the East of England, London and the South East.The alerts will remain in place until 5pm on Wednesday and replace less severe yellow alerts, which were previously issued. WEYMOUTH -- Crowds of visitors are seen sunbathing and splashing in the sea at the beach today SUNDERLAND -- Revellers at BBC Radio 1 Big Weekend today enjoying the bank holiday weekend weather WOLVERHAMPTON -- Summer, Robyn, Vinnie, Maddie and Daisey Lane cool off in Tettenhall Pool todayThe alerts mean there is likely to be 'a rise in deaths, particularly among those aged 65 and over or with health conditions' and increased demand on all health and social care services, according to the UKHSA website.Yellow alerts have been issued for the North East and North West, Yorkshire and Humber, and the South West.The scorching heat has led Marylebone Cricket Club to dispense with its strict dress code in the Lord's Pavilion. The club said gentlemen would not need to wear jackets in the pavilion for a match between Middlesex and Surrey today. Met Office Deputy Chief Forecaster, Steve Kocher, said: 'Temperatures are forecast to peak on Monday when we could see 33C recorded in southern England and the Midlands.'It is likely that the May and spring UK temperature records will be broken over the bank holiday weekend, with forecast temperatures surpassing the existing record of 32.8C. 'As well as it being hot, there will be lots of dry and sunny weather for much of the UK. There will, however, be more cloud and some showers in Northern Ireland and western Scotland through the weekend. 'With relatively low sea surface temperatures there is also likely to be some low cloud and sea fog clinging closely to western coasts.'Saturday also saw holidaymakers trying to get to Europe via the Port of Dover where they faced hours-long queues.In a bid to ease the waits, the French authorities suspended extra EU border checks under the new entry/exit system (EES).EES involves people from third-party countries such as the UK having their fingerprints registered and a photograph taken to enter the Schengen Area, which consists of 29 European countries, mainly in the EU.By Saturday late afternoon, the port said the traffic was 'free flowing' on its 'peak day of the May half-term getaway weekend'. Amber heat health alerts were issued by the UK Health Security Agency on Friday morning for the East Midlands, West Midlands, the East of England, London and the South East Britain yesterday saw the hottest day of the year when the village of Frittenden, in Kent, hit 30.5C LONDON -- A man tells his pet dog to go fetch at the water fountains in Battersea Park today SUNDERLAND -- Revellers at BBC Radio 1's Big Weekend pose for a photo LONDON -- A woman sits near the water fountains in Battersea Park today and takes a photo with her mobile phone KENT -- A man paddles along the Great Stour river in Upstreet village as amber health alerts are issued across the UK for a weekend heat wave BLACKPOOL -- An elderly woman holds an ice cream as she coos at a child in a pram yesterday BLACKPOOL -- Children ride donkeys along Blackpool beach on Saturday as Britain recorded its hottest day of the year so far FALMOUTH -- Crowds gather at Gyllyngvase beach yesterday to enjoy the hot weatherMet Office meteorologist Jonathan Vautrey said there will be 'plentiful amounts of sunshine for the vast majority' of people on Sunday, but it looks set to be a damp day in parts of the North West and Scotland.The MCC, which owns Lord's, said it has 'decided to dispense with the requirement for gentlemen to wear jackets in the pavilion' for two Vitality Blast matches on Sunday.Most will also see 'wall-to-wall blue sunshine' on Monday, Mr Vautrey said.The meteorologist continued: 'That extra sunshine once again allowing those temperatures to climb even further and so now we're expecting to see around 33C in the far south-east of London but quite broadly a potential for 30C into parts of northern England, areas of Wales and right throughout the Midlands as well.'If we hit that 33C, maybe even locally close towards 34C, that would bring us our hottest bank holiday day on record, as well as our hottest day in May on record, so it really is quite exceptional heat that is building for the time of year.'During the heatwave, people have been advised to keep their homes cool by closing windows and curtains in rooms that face the sun. They should also seek shade and apply sunscreen regularly, and are advised to keep out of the sun between 11am and 3pm.Physical activity such as exercising or walking a dog should take place in the morning or evening when temperatures are cooler.People have also been advised to look out for signs of heat exhaustion and heatstroke. A UK heatwave is official when a location records at least three consecutive days of daily maximum temperatures which meet or exceed a specified threshold - which varies by region Sunseekers cool off in the sea off Brighton, East Sussex, on Saturday People are pictured enjoying the sunshine at the Strand Lido in Gillingham today LONDON -- A hot weather reminder was displayed on the big screen yesterday at Wembley stadium during the Championship play-off final between Hull and Middlesbrough Traffic queuing for the Euro Tunnel site along the M20 motorway in Folkestone, Kent, on Saturday LONDON -- People are spotted using umbrellas to shield themselves from the sun's rays in the capital yesterday Heat exhaustion symptoms include tiredness, feeling faint, intense thirst, heavy sweating, and feeling or being sick.Signs of heatstroke include confusion, lack of co-ordination, a fast heartbeat, hot skin that is not sweating, and seizures.A heatstroke is a medical emergency and people are advised to call 999 if they believe someone is experiencing one, according to UKHSA.Dr Anya Gopfert, Consultant in Health Protection at UKHSA, said: 'We know that even moderate heat can lead to serious health problems, especially for older people and those with certain health conditions, so it's important that everyone takes simple precautions while enjoying the warm weather over the coming days.'If you have friends, family or neighbours who are more vulnerable, it is important to check in on them and ensure they are aware of the forecasts and are following the necessary advice.'