The National Weather Service says very warm temperatures are in store for San Diego County through Friday.
That means temperatures across the far inland valleys top out in the upper 90s, with a few locations possibly at or even above 100 degrees.
"The temperatures across the mountains and deserts will also be above normal. However, afternoon showers and temperatures will help moderate temperatures during the late afternoon and early evening," according to the Weather Service.
Coastal areas are expected to be in the high 70s to low 80s, or about 5 degrees above normal for this time of year.
"Needless to say, summer is not over and muggy conditions will prevail," the NWS said, noting that those sensitive to heat should take precautions, including staying indoors and drinking plenty of water.