National weather service warns people to stay indoors and electricity companies warn of power outages A swath of America from the Mexican border to Boston suffered under dangerously hot temperatures on Friday, as a heatwave that has killed at least 22 people continued into the weekend. The combination of high temperatures and excessive humidity has triggered health warnings across the country. At least 50 cities hit 110F (43C) on the heat index on Thursday. On Friday, Washington DC, Tulsa, Oklahoma, Buffalo in New York and other cities’ temperatures climbed into the triple digits by noon. The national weather service said excessive humidity would make it feel even hotter. With the heat index, Washington reached 113 degrees by 11am. Nearby Richmond and Baltimore were on track to reach 120 degrees. At least six people died in heat-related deaths on Thursday. Many of the victims have been in the midwest, including a cook in Michigan who suffered a heart attack when he was sent home from work. The heatwave has also triggered a spate of medical emergencies. A girl scout group was treated for heatstroke at a camp in Connecticut. In Pittsburgh, a man fixing the roof at his cousin’s home was stuck in the blazing sun for nearly two hours because of the melting tar, Associated Press reported. With no relief until Sunday, the national weather service issued a series of warnings, advising people to stay indoors in an air-conditioned environment and reschedule strenuous activities. Residents in several cities were warned to watch out for poor air quality. “Do not take this threat lightly,” the weather service said in a statement on its website, noting the extreme temperatures are particularly dangerous for the elderly and the very young. “The length of this heatwave will pose a very real and dangerous health risk to these already at-risk groups and those that do not have access to air-conditioning,” the statement added. Local authorities in several cities opened cooling centres. Manhattan sent a water truck to cruise the city streets. Philadelphia cancelled summer school programmes. The extreme heat was also bearing down on the electric grid, as people on the heavily populated east coast turned up their air conditioners to try to keep cool. Electricity companies in a number of localities warned of possible power outages. In New York City, meanwhile, people hoping to beat the heat with a swim outdoors were advised to stay away from city beaches after a fire in a water treatment plant sent raw sewage cascading into the Hudson river. United States Natural disasters and extreme weather Suzanne Goldenberg guardian.co.uk