Friday is expected to be the hottest day of the week with triple-digit temperatures hitting much of the Central Valley, according to the National Weather Service.
Forecasters say temperatures in Northern California will be about 15 to 20 degrees higher than normal.
Despite the heat, water safety is still a concern. People heading to streams and rivers should be careful of cold and fast-moving water.
Officials are also cautioning that heat-related illnesses are a possibility for sensitive groups.
The city of Rancho Cordova has opened a cooling center to help residents beat the heat.
Starting from noon to 5 p.m., on Friday and Saturday, the cooling center will be opened at Prospect Park Drive. Complimentary water and snacks are available, though pets are not allowed.
By Saturday and Sunday, the region will see scattered thunderstorms as an upper level system moves through the state. The Sacramento Valley could see some rain Saturday night and into Sunday morning.
The NWS says a transition from a hot stretch into a thunderstorm event has historically led to increased fire starts.
-Capital Public Radio Staff