A persistent heat wave that scorched most of California earlier this month essentially amounted to a real-time stress test that the state’s electric grid managed to withstand. But the head of the organization responsible for keeping the lights on says energy officials are still on alert as the summer wears

July’s second major heat wave isn’t forecast to be as extreme as the last event, which set several all-time records for high temperatures. Nevertheless, the National Weather Service predicted that it will be a “long-duration heat wave,” which creates uniquely dangerous conditions — especially when temperatures barely drop at night.

South Lake Tahoe will see a similar spike in hot days, but with temperatures only reaching the mid 80s. Lows at night will go down to 60 degrees, according to the NWS forecast.