Why the heat index matters more than the temperature in this heat wave

(CNN)Checking the temperature reading during this weekend’s heat wave won’t tell the whole sweltering story. It’s going to feel a lot hotter. So, Washington — with a predicted temperature Saturday of 100 degrees Fahrenheit and relative humidity of 73% — can expect it to feel like 111 degrees, she said. And Boston’s forecast high temperature of 97 degrees, with relative humidity of 71%, will make it feel like 105. And that’s not even in the sun. “When we, as meteorologists, forecast the high temperatures or the heat index, that is in the shade,” Brink said. “The sun definitely makes it worse.” In “direct sunlight, the heat index value can be increased by up to 15 degrees Fahrenheit,” according to the …