The National Weather Service has issued a Heat Advisory for San Diego County inland valleys, warning that high temperatures could reach the mid-90s to 105 on Thursday and Friday. The advisory is in effect until 8 p.m. Monday, according to the agency's active alert for the Santee area.

Forecasters also warned that overnight temperatures may stay unusually warm, with lows in the 70s expected for inland valleys on Friday and Saturday. That matters because warm nights can make it harder for homes to cool down between daytime heat peaks.

The weather service said hot temperatures may cause heat illnesses and urged residents to drink plenty of fluids, stay in air-conditioned spaces, avoid prolonged sun exposure and check on relatives and neighbors.

For Santee, the alert lines up with the kind of inland heat pattern that can hit neighborhoods away from the coast harder than beach communities. Residents with outdoor plans, youth sports, pets or older family members should build in shade, water breaks and cooling time.

Residents can follow the latest alert status through the National Weather Service San Diego active alert page.