heatwave mountains
The San Diego mountains on a hot day. Photo via @JenDelacruzTV Twitter

A new excessive heat warning went into effect Sunday for the San Diego Mountains just one day after a previous advisory expired, the National Weather Service said.

The new warning was in effect through 8 p.m. with temperatures ranging from 91 to 100, with wind gusts of up to 25 mph and a 40% chance of precipitation. It replaced a similar advisory that expired at 7 p.m. Saturday.

The NWS reported that Sunday temperatures in the deserts ranged from 109 to 112 degrees.

Sunday night was expected to see a chance of showers and thunderstorms, mainly after 11 p.m., with a low of around 74 degrees. Conditions were expected to be partly cloudy, with a 30% chance of precipitation.

Monday was forecast to cool down a bit, with a high near 88 degrees with partly sunny conditions, a chance of showers and thunderstorms, and a 50% chance of precipitation in general.

That night, there is a slight chance of showers and thunderstorms. Conditions are expected to be mostly cloudy, with a low of around 72 degrees, and a 20% chance of precipitation, according to the NWS.

Meanwhile, a weak coastal eddy cooled coastal areas with low clouds and sea breezes.

Flow around strong high pressure centered over Colorado, are steering monsoonal moisture and disturbances, creating the chance for the occasional showers and thunderstorms.

The action should start over the mountains Sunday, peak Monday when a few showers and storms will make it west of the mountains, then wind down on Tuesday, according to the weather agency.

The atmosphere will dry and cool a bit after Tuesday as the high subsides before heating up again next weekend.

City News Service contributed to this article.

Updated 7:40 p.m. July 30, 2023