If you're looking to stay cool the next few days in Southern California, head to the beach or find a place with air conditioning.

The National Weather Service has issued an Excessive Heat Warning for much of Southern California beginning Friday, with temperatures expected to range from 100 to 105 in the foothills and lower mountain slopes.

"Children, the elderly and people with chronic ailments are the most susceptible to heat-related illness. Heat exhaustion, cramps or in extreme cases heat stroke can result from prolonged exposure to these conditions," warned an NWS advisory. "In addition, with very dry vegetation, fire danger will also be on the rise. Be extra cautious with outdoor activities that may result in fire ignitions."

L.A. County has opened cooling centers (map) throughout the region for residents to escape to for the heatwave's duration.

The forecast is even hotter for the lower deserts: 115 to 120 and about 110 in the upper deserts. In Riverside County, temperatures are forecast to range from 100 to 110. The heat is expected to last through Sunday but could be extended into next week.

But the humidity is expected to be low during the heat wave.

"So at least we won't have the situation where it feels hotter than it is, but with temperatures in some areas between 110 and 120, if you feel slightly cooler, it's still going to be very, very hot," said National Weather Service meteorologist Brandt Maxwell.

Heat and low humidity are ripe conditions for fires. The National Weather Service advises people to drink ample amounts of water and and stay inside, if possible, in an air-conditioned building.

The Excessive Heat Warning will be in force from 10 a.m. Friday until 9 p.m. Sunday in the San Gabriel Mountains and the Antelope Valley. In the San Fernando, Santa Clarita and San Gabriel valleys, the warning will be in effect from 10 a.m. Saturday until 9 p.m. Sunday.

If you're going to the beach to escape the heat, you might find some hazardous conditions too. The National Weather Service said there is also a high rip current risk at many Southern California beaches through Friday night. And, for boaters, there is a small craft advisory for waters off the coast. The advisory is in effect until 3 p.m. Saturday.

A map showing the heat warning from the National Weather Service:

A video detailing the heat warning from the National Weather Service: