Thunderstorm over Mt. Laguna
The thunderstorm over Mt. Laguna on Wednesday afternoon. Photo from UCSD HPWREN camera network

Thunderstorms are expected to develop over the back country mountains for the third day in a row on Thursday, but the monsoonal moisture will give way to another heat wave peaking next week.

Flash flooding is possible again in the mountains and desert slopes, but a warming trend will begin Friday.

“Strong, upper-level high-pressure builds back over southern California late Sunday through early next week,” the National Weather Service office in San Diego said. “This will result in a significant warming and heat wave for inland valleys, deserts and mountains.”

The weather service forecasts peak highs next week ranging from the mid 80s to low 90s along to coast, mid 90s to low 100s in the inland valleys, and the mid to high 110s for the San Diego County deserts.

Coastal areas will be spared the worst of the heat because of low clouds and a daily sea breeze, but it will still be muggy because of warm ocean temperatures.

The weather service also warned of elevated wildfire danger due to hot temperatures and much drier air for inland areas.

Chris Jennewein is Editor & Publisher of Times of San Diego.