Warm Winds Expected to End Cold Weather

Cool nights that brought freezing temperatures to agricultural areas this week are expected to warm this weekend as winds from the West replace cold northern air.

According to the National Weather Service, upper-level winds blowing into San Diego County will shift today, bringing in warmer air from Hawaii. The changing pattern should moderate chilly nighttime temperatures and raise daytime highs to near average.

A frost advisory was issued to growers several nights this week, and lows dipped to the 20s and 30s in the coldest areas. Mountain and desert lows, although still forecast to be cool, should rise by 5 to 10 degrees. Inland lows are expected to rise to the 40s, and coastal lows may reach the 50s over the weekend.

Slightly warmer, sunny days are expected through Saturday with near normal highs, but according to forecaster Wilbur Shigehara, the westerly winds blowing in warmer air could also bring in a storm on Sunday.

“A storm near the Hawaiian Islands is edging eastward, and it looks like clouds might come in on Sunday. It doesn’t look like a big storm, but it could bring rain early next week,” Shigehara said.

A high-pressure system has been fostering mild San Diego weather this week, except for a brief visit by a low-pressure system Thursday morning that brought clouds and some drizzle. Shigehara said pressures were building again Thursday and a high-pressure system over San Diego might divert the storm to the north. But he could not predict the path of the impending storm on Thursday.

The influx of western air should also raise this week’s below-average relative humidity to normal levels of 55% to 60%. Shigehara said a weak Santa Ana condition this week had dropped the humidity about 20%.

“People think Santa Anas are hot, but we have cold Santa Anas too,” Shigehara said.

In mountain areas this weekend, temperatures in the 40s and 50s during the day may fall to around 30 at night.

Desert highs in the 60s under sunny skies are expected to dip into the 30s at night, and inland valley and coastal strip highs in the 60s today may reach the 70s Saturday. Lows are expected to be in the 40s inland and up to 52 degrees along the shore.