As Individuals come out to commemorate the nation’s 250th birthday on Saturday, the temperatures throughout enormous swaths of the nation will probably be something however celebratory. An intense warmth wave is settling over the East and Central U.S., exposing tens of millions to temperatures above the seasonal common and placing them susceptible to heat-related diseases.

Up and down the East Coast and the Central U.S., the mercury might surpass 100 levels Fahrenheit (38 levels Celsius), with some locations, corresponding to New York Metropolis, doubtlessly feeling as scorching as 115 levels F (46 levels C) through the day. The best strategy to keep protected is to stay indoors in air-conditioned areas with easy accessibility to chilly water—each for consuming, and for showering or wetting towels to chill your physique. However that received’t work for everybody.

Most public well being messaging throughout a warmth wave focuses on two heat-related diseases: warmth exhaustion and warmth stroke. And for good purpose: warmth stroke, the extra severe situation, can happen when the physique’s inner temperature rises above 104 levels F (40 levels C) or by excessive dehydration. Warmth stroke will be deadly with out quick medical consideration.