Britain basked in the hottest day of the year so far today as an 'exceptional' week-long heatwave began with temperatures set to hit a record-breaking 34C. Temperatures reached 28.4C in Cambridge, Heathrow and Cranwell, Lincolnshire according to the Met Office, beating the previous 2026 record of 26.6C observed in London on April 8. Forecasters expect the UK will have its warmest-ever May day and spring day over the bank holiday weekend as families embark on their half-term holidays. The mercury will rise further to 29C tomorrow, 31C on Sunday and then peak at 34C on Monday. Tuesday will be 32C then Wednesday and Thursday will both be 29C. Any temperature above 29.4C will be the warmest May day recorded in the UK since 2012 – while the current May temperature record is 32.8C in London in 1922. High pressure will bring settled conditions and clear skies, as the Met Office declared an 'exceptional spell of warmth for May with a notable heatwave forecast'. The UK Health Security Agency (UKHSA) issued a six-day amber heat health alert for southern, eastern and central England from today until Wednesday – which was upgraded from yellow. The rest of England has a yellow alert for the same period.The amber alert warns 'significant impacts are likely across health and social care services' – including 'a rise in deaths, particularly among those ages 65 and over or with health conditions' and 'there may also be impacts on younger age groups'. Temperatures in London will hit at least 28C for a week from today, according to the Met Office People enjoy the hot weather on Sunny Sands beach in Folkestone, Kent, this afternoon People enjoy the warm weather in Aldgate Square in London today as the heatwave begins Visitors enjoy the hot weather on Weymouth beach in Dorset this afternoon A woman walks her dog through Hampstead Heath in North West London this afternoon People enjoy the hot weather at Chesil Beach in Dorset today as they head to the coast A couple walk on the Victoria Embankment today, with the London Eye seen in the background A man runs along the Regent's Canal in London today as heat health alerts are implemented People sunbathe on the beach at Dover in Kent today as ferries can be seen next to the port A sunny day for the Duke of Edinburgh Gold Award celebrations at Buckingham Palace today People cycle along the seafront at Southend-on-Sea in Essex today as the heatwave begins Leon, 5, plays in fountains at Coal Drops Yard in London today as health warnings are activated People enjoy the warm weather while sat on the grass at St James's Park in London todayThe UK Health Security Agency has activated a heat health alert from today until WednesdayThe Government agency also said there will be 'likely increased demand on all health and social care services', while 'internal temperatures in care settings - hospitals and care homes - may exceed recommended threshold for clinical risk assessment'.The heat is also expected to affect the 'ability of the workforce to deliver services' and could see 'indoor environments overheating increasing the risk to vulnerable people living independently in community and care settings'.Other warnings include 'issues managing medicines'; 'staffing issues due to external factors - for example, affecting transport'; 'increased demand for power exceeding capacity'; and 'other sectors starting to observe impacts - for example, travel delays'.The UKHSA advises anyone doing physical activity such as exercise or walking the dog to carry this out when it is cooler such as in the early morning or the evening - and try to avoid direct sunlight between 11am and 3pm when UV levels are highest.Those who are going out during the hottest parts of the day should 'cover up with suitable clothing, wear a wide-brimmed hat and sunglasses, seek shade and apply sunscreen liberally and re-apply frequently'.Heatwave thresholds - defined as three days in a row at or above a set temperature, which is 28C in London - are likely to be reached in the South East from Sunday.As the weekend progresses, these very hot conditions will become more widespread - extending across central and western England and into parts of Wales.Met Office deputy chief forecaster Steve Kocher said: 'Temperatures will climb through the weekend, especially in the South, where 30C is likely to be recorded on Saturday and 32C on Sunday.'Temperatures are forecast to peak on Monday when we could see 33C recorded in southern England and the Midlands.'Met Office forecast data for London suggests the temperature could peak even higher in London at 34C.Mr Kocher added: '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.'Network Rail warned passengers that the hot weather could disrupt train services, given heat can cause lineside fires, rails to buckle or overhead lines to expand and sag. Temperatures in the UK are expected to exceed those forecast in Barbados as well as Mediterranean hotspots including Mykonos, Rhodes and Santorini over the weekend.Winds are turning more southerly by the end of the week, but the high temperatures are not primarily due to hot air being transported directly from southern Europe or North Africa.A Met Office spokesperson said: 'Instead, the main driver of the warming trend is the development of high pressure over and near the UK. As this high-pressure strengthens, it causes sinking air in the atmosphere.'This descending air is compressed as it moves downward, leading to warming through a process known as adiabatic compression. In simple terms, as air is compressed, its temperature increases.'This process can significantly raise temperatures at the surface, even when the original air mass is not especially warm. In this case, much of the air over the UK still originates from the Atlantic, but it becomes warmer as it descends under high pressure.'This mechanism is a common feature of warmer spells in the UK and is often more important than the transport of heat from lower latitudes.'Meanwhile people are being urged to check water quality in bathing spots and sea conditions along coasts before swimming as the UK braces for the scorching weather.The Met Office is encouraging the public to be 'weather ready' by making informed choices on swimming and locations as they head outdoors or to the coast to enjoy the sunshine.Campaign group River Action warned of the health risks posed by poor water quality, even in designated bathing spots.Alzheimer's Society said people with dementia are likely to be more vulnerable in warmer conditions and outlined measures others can take to support them.Jo Crossland, head of dementia and lifestyle at Care UK, said: 'If an older relative puts on a thick jumper or heavy layers in the middle of a heatwave, it could be a sign they're misjudging temperature – something that can happen if a person has problems with their thyroid gland or could even be an early indicator of dementia.'It is not uncommon for people with memory problems to become confused about the right clothes to wear for the weather failing to recognise how warm it really is. 'This can lead to the person reaching for heavier clothing out of habit which traps heat and can quickly lead to overheating and the risk of dehydration.The British Heart Foundation said heart patients also face potential dangers in the heat and should take extra precautions to minimise health risks.Hotter conditions often lead to a surge in ambulance call-outs and Royal National Lifeboat Institution (RNLI) rescues along UK coastlines as people experience heat stress or get into trouble in the water.The Met Office is advising the public to take care with sun protection and check their local weather conditions, using tools such as 'beach forecasts' on its app to help them make informed choices.Holly Clements, Met Office head of warnings and guidance, said: 'Warm weather on a bank holiday draws people outside, but the weather at the coast can change quickly, and conditions like tides, waves and wind can all affect safety at the beach.'Sun protection is particularly important here as reflective surfaces like sand and water amplify UV radiation that can damage skin and eyes, even when it's cloudy.'By checking the forecast and following simple safety advice, people can reduce the risks and make the most of their time by the sea.'The RNLI said choosing a lifeguarded beach, swimming between the red and yellow flags, and educating themselves on what to do in an emergency can make all the difference in staying safe on the coast. 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 regionLast year, the organisation helped to save more than 36,000 people across UK beaches, which was more than double compared with the previous year.Samantha Hughes, RNLI water safety partner, said: 'If you find yourself in difficulty in the water, try to remain calm and remember Float to Live: lean back with your ears submerged, extend your arms and legs, and float until you can control your breathing and wait for help to arrive or before moving to safety.'If you see someone else in trouble in the water, phone 999 or 112 and ask for the coastguard.'The public is also being urged to check the water quality before entering rivers, lakes or coastal waters ahead of the bank holiday weekend, after the official bathing season began last week.Between May and September, 464 sites across England's coasts, rivers and lakes are subject to regular water quality testing by the Environment Agency.Poor water quality caused by sewage spills and pollution in many of the country's waterways can put people's health at risk with illnesses such as E.coli or norovirus, as well as skin, eye and ear infections.River Action said swimmers, paddlers, rowers and bathers can check for recent sewage spills or water quality alerts near designated bathing sites through tools such as sewagemap.co.uk or Surfers Against Sewage's 'safer seas and rivers service'.The group also encourages people to refer to practical guidance developed in partnership with British Rowing and The Rivers Trust on reducing health risks and staying safe when water quality is poor.James Wallace, River Action chief executive, said: 'In general, dry weather can mean lower pollution risk, but people should still take care, avoid swallowing water, and avoid swimming with open cuts or wounds.'Elsewhere, Alzheimer's Society said people can support loved ones or neighbours with dementia by leaving drinking water within easy reach and ensuring they opt for light-coloured, airy clothes, stay out of the sun between 11am and 3pm, take cool showers and keep blinds closed.Angelo Makri, senior knowledge officer for wellbeing at Alzheimer's Society, said: 'People should absolutely enjoy the nice weather we're having, however, it's important to note that high temperatures can lead to severe health problems for people with dementia unless they take precautions to keep cool and well hydrated.'And the British Heart Foundation said those with heart conditions face specific risks because the organ has to work harder to keep the body's core temperature at normal levels while blood vessels dilate, which can lead to a drop in blood pressure.Ruth Goss, senior cardiac nurse at the foundation, said: 'In hot weather, check on your friends and relatives regularly to make sure they are cool and comfortable.'The most important way you can protect your heart in the heat is to stay cool and keep hydrated.'Cllr Dr Wendy Taylor, chair of the Local Government Association's Health and Wellbeing Committee, said: 'With a heatwave expected to cover large swathes of the country this weekend, people in affected areas can help to identify those who may need advice or practical help during the high temperatures.'Look out for those who are more vulnerable – older people, young children, babies, and those with underlying health conditions.'Hot weather advice applies to everyone, not just those who are vulnerable. It may feel like common sense, but we can all take sensible precautions during the high temperatures.'A spokesperson from Marie Curie, said: 'The end-of-life charity Marie Curie is warning that people living with a terminal illness may be among those particularly vulnerable to the effects of hot weather, as high temperatures can be especially difficult for people with a terminal illness, who may experience changes in body temperature and excessive sweating.'The charity is encouraging people to take simple steps to stay comfortable, including keeping rooms cool and ventilated, using fans or cooling sprays, layering clothing and bedding, drinking water or sucking on ice, reducing caffeine, and choosing breathable fabrics such as cotton or silk.'Anyone worried about sweating or temperature changes should speak to their doctor or healthcare team.'Vets have also warned pet owners to watch their animals for signs of overheating and make sure they stay hydrated by leaving plenty of water out.'With the Met Office forecasting temperatures of above 25 degrees this weekend, the UK is bracing for an intense heatwave that will put both people and pets to the test,' a spokesperson for veterinary care provider Medivet & Partners said.'As pets are unable to communicate when they are overheating, or struggling with dehydration, they are at risk of suffering in extreme conditions more than most.'Pets suffering a heatstroke may display symptoms such a excessive panting or thirst, very red gums, lethargy, and vomiting and diarrhoea.Pet owners should react by soaking their pet with cool water – or even non-toxic fluids such as cold fizzy drink, if water is not available – then contact their vet for advice.Dog owners have also been advised to restrict their walking routine to cooler times of the day.'On extremely hot days, dogs will benefit from skipping a walk completely, as evenings and early mornings are still hot enough to trigger heatstroke,' Dr Rhian Littlehales, clinical governance director at Medivet & Partners, said.'If you're not sure if the pavements are too hot, place the back of your hand on the ground for seven seconds.'If you struggle to hold it down, it's too hot to walk your dog.'The Met Office said a climate attribution study published last summer by its scientists found that the 'chances of surpassing the May temperature record set in 1944 have been increasing as our climate changes as a consequence of human greenhouse gas emissions'.A spokesperson added: 'The study found that breaking the 32.8C May record is around three times more likely now in our current climate than it would have been in a natural climate not impacted by greenhouse gas emissions. What was around a 1-in-100 year event is now around a 1-in-33 year event.'Retailer Lakeland said sales of ice cream makers were up by 500 per cent against the same time period last month; cool bags had jumped by 262 per cent; and pizza ovens and BBQs increased by 108 per cent. Asda said searches for ice cream were up 900 per cent, ice lollies by 202 per cent and paddling pools up 1,175 per cent.The supermarket added that sales of shorts are up 65 per cent and sandals and flip flops up 75 per cent.Searches for beer are up 7 per cent while rosé and white wines are up 36 per cent and 22 per cent respectively. Gordon's sprits are up by an astonishing 14,000 per cent, while cider cans are up 200 per cent.Vineyard owners have also welcomed the heatwave after an unusually cool May so far.Ceri Phipps, owner and founder of Two Beacons Vineyard on the Herefordshire and Worcestershire border, said: 'With the recent unseasonable threat of frost, this heatwave can't come soon enough to bring on the vines for harvest later in the year, and pave the way for our next vintage.'The National Pharmacy Association said patients should store medicines safely at temperatures below 25C during the heatwave.Its experts warned that when temperatures climb, medicine can lose its effectiveness or even cause unwanted side effects in some cases.People with asthma should also remember to take their preventor inhalers, given warmer weather can be a trigger for asthmatic symptoms.Olivier Picard, chair of the National Pharmacy Association, said: 'Although we can enjoy hot weather, heatwaves can quietly affect our bodies, our breathing, and even the way our medication works'It's important we take sensible precautions, including double checking that your medication is stored correctly in a cool dry place as per any storage instructions, ideally below 25C, as well drinking plenty of fluids and keeping your home cool in the hottest hours of the day.'We know the hot weather can be more of a challenge for older people or those with certain health conditions and it's important people check on vulnerable friends, family and neighbours during this period.'The Royal Society for the Prevention of Accidents urged people planning a barbecue this weekend to take extra care, after new figures from the Children's Burns Trust showed 215 youngsters required hospital treatment for serious barbecue-related burns last year. Bookmaker William Hill said it had to cut the odds on bank holiday Monday to be the UK's hottest on record to 8/11, after quoting at evens yesterday. Yesterday's top UK temperature was 24.6C at Heathrow Airport, followed by 23.3C at Kew Gardens.