Elsewhere pupils were sent home from a school in East Yorkshire after refusing to wear blazers as temperatures soared past 86F (30C).Kingswood Academy in Hull said the children were defiant over their uniforms, but parents complained that teachers had put their health at risk.Allergy charities also warned that the hot weather could trigger fatal attacks and said sufferers should stay away from rural areas and avoid leaving windows open at night and early in the morning when pollen counts were at their highest. Gritters were deployed to shore up failing roads as temperatures on the surface reached 104F (40C), causing them to melt.Cambridgeshire County Council took the decision to deploy the vehicles after motorists complained that their tyres had started ‘ripping the tarmac off the roads.’ Show more A group of actresses enjoy the warm weather in Green ParkCredit:Anja Riedmann / Barcroft Images “Our engineers are on site and, as is standard procedure, they are applying sand to mitigate the effect of the heat.” However the scorching give day heat wave will come to an end with thunder and hailstorms with 1.6 inches of rain expected to fall in an hour on Wednesday evening, sending temperatures plummeting. Drivers were warned by police to take care on the B1165 near Newton in Cambridgeshire, where the tarmac has melted, and Agnes Owen, who works at a service station nearby, said that it ‘sounded like cars were driving on water.’Evan Laughlin, from Cambridgeshire County Council, said gritters had been used to distribute granite dust to stabilise the road surface and stop bitumen becoming stuck on wheels. “Normally the roads stand the summer temperatures we get, but just this week it’s very hot,” she said. Asthma UK’s in-house GP Dr Andy Whittamore said: “The hot weather can trigger asthma symptoms in some people, increasing their risk of having a potentially life-threatening asthma attack.“People with asthma need to be on high alert as their airways may already be inflamed from high levels of pollen, which is a trigger for around 80 per cent of people with asthma. Heat and pollen can be a dangerous combination”.Allergy UK’s Nurse Advisor, Holly Shaw, said sufferers should shower and wash their hair after arriving home to reduce the symptoms and consider staying indoors when the pollen count was very high. Laura Paterson, Met Office chief forecaster, said: “Temperatures will peak on Wednesday. There will be torrential downpours and hail and this will see temperatures begin to come down.”The weekend is relatively unsettled, with more rain likely but there will be a fresher feel from Thursday.”The storm will move in from the west to affect parts of southern Scotland and northern England from the early hours of Wednesday.More extensive thunderstorms may then break out over a larger part of England and Wales from late Wednesday afternoon onwards into Wednesday night, leading to torrential downpours, frequent lightning and a chance of hail. Fans put on their sun cream due to the hot weather on day two of the 2017 Aegon Championships at Queens ClubCredit:Patrik Lundin/Getty Images for LTA Motorists in Tarleton, Lancashire also discovered tar on their wheels as the roads melted., while some commuters in Croydon refused to use trams after noticing the track appeared to be disintegrating. Transport for London said they had thrown sand down to help protect the rails.Rory O’Neill, TfL’s Director for London Trams, said: “The flexible sealant near the track has been softened by the current hot weather and although it is having no impact on the safe running of the tram network, we appreciate it may look concerning to customers. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.