A punishing heat wave will test power supplies in Texas for a second day as triple-digit temperatures continue to drive up electricity consumption.

The state’s grid operator expects to have almost 80 gigawatts of capacity available at about 8 p.m. local time, after solar farms start shutting off, based on hourly forecasts. Demand will be within about 1 gigawatt of that total. Five-minute forecasts show demand exceeding supply around that time, according to data from Nrgstream.

The renewed constraints come after Texas narrowly avoided imposing rolling blackouts Thursday. Officials had warned they might need to declare an energy emergency as the grid faced its most serious test so far this summer, but cooling rains unexpectedly tempered demand as the sun went down. While the state has been adding capacity, the population has also been increasing, which will tax the grid when temperatures soar.

“Lots of people have moved here, and they all want air conditioners,” said Joshua Rhodes, an energy research scientist at the University of Texas at Austin.

The heat wave that’s been blanketing the central US all week is winding down, but it’s not over yet. Excessive heat warnings and heat advisories are in place across parts of 19 states including Texas, Louisiana and Illinois.

Read more: Surprise Thunderstorms Spare Texas From Blackouts — For Now

Houston tied its hottest day in records going back to 1889 when the temperature hit 109F (43C) Thursday, the National Weather Service said.

Friday’s high temperature in Houston is forecast to reach 102F, and when humidity is added to the mix, it will feel closer to 111F. In Dallas, readings could reach 108 with a heat index of 113F.

--With assistance from Brian K. Sullivan and Rachel Adams-Heard.