A dangerous heat wave is predicted to smother California this Labor Day weekend, increasing the risk of fire as crews continue to tackle record-setting blazes across the state.

The National Weather Service has issued an excessive heat warning for much of the state, with temperatures predicted to rise 20 to 25 degrees above normal, outdoing a mid-August heat wave that scorched the western United States and precipitated rolling blackouts across California.

The state’s grid operator has issued a flex alert urging customers to conserve energy throughout the three-day weekend.

Fire crews are on high alert as dry conditions and gusty winds threaten to exacerbate dozens of wildfires burning across the state, three of which have become some of the largest in California state history. The SCU Lightning Complex Fire, burning in the San Francisco Bay Area and parts of the Central Valley, is now the 2nd largest wildfire in California history, having torched nearly 400,000 acres since igniting August 18, according to Cal Fire.

With soaring temperatures comes an acute risk of heat related illness, including dehydration, heat exhaustion, and heat stroke — conditions that can be deadly, particularly for elderly populations and those who work outdoors. In the United States, heat is the leading cause of weather related deaths.

The National Weather Service is recommending people stay in air-conditioned rooms to prevent overheating — a measure that may now carry health consequences amid the Covid-19 pandemic. According to a group of Harvard epidemiologists, air conditioning may accelerate the spread of Covid-19 by re-circulating viral droplets and is a likely contributor to the case spike that tormented the South in June, as people migrated indoors to avoid hot weather.

In addition, officials are encouraging people to drink plenty of water, stay of out of the sun, and check in on neighbors and relatives, particularly the elderly and very young.

Direct Relief is prepared to deploy emergency medical supplies overnight in response to fire-related health conditions. In addition, the organization has equipped several health facilities with backup power units to increase resiliency in the case of an electrical outage.

Direct Relief will continue to monitor the situation throughout the weekend and respond to health needs, should they arise.