Most sweltering US city Thursday? Not Phoenix. Not even Houston. It was Fort Worth.

Forget Phoenix, Las Vegas or even Death Valley, California. On Thursday, it was Fort Worth that felt the most sweltering in the grip of the heat wave across the lower half of the country.

With a heat index of up to 116 degrees, Cowtown ranked No. 1 in the U.S. among large cities, according to an analysis by The Washington Post. Austin and Dallas followed with a heat index of 114 degrees. Even Florida’s merciless humidity couldn’t surpass the misery in North Texas; Jacksonville ranked 10th among cities with a heat index of 105, the Post reported.

In Phoenix, where it was 112 degrees on Thursday, lower humidity meant a heat index of only 110.

Heat index is the “feels like” temperature, factoring in humidity. This summer’s scorching temperatures have already sent hundreds of people in Fort Worth to hospitals for heat-related illnesses.

An excessive heat warning is in effect for Fort Worth and surrounding cities until 9 p.m. Thursday as temperatures will be as high as 95 to 109 degrees with a heat index ranging from 105 to 114 degrees, according to the National Weather Service’s Fort Worth office.

The weather service recommends drinking plenty of water, avoiding excess time outside, wearing light-colored and breathable clothing, and by taking frequent breaks in the shade when outdoors.