SAN DIEGO - Parts of San Diego saw frost Thursday as temperatures dropped in the 30s.
The National Weather Service in San Diego issued an overnight frost advisory for the lower Coachella Valley, areas around the Anza Borrego Desert and coastal plains east of the Interstate 5 corridor late Wednesday to early Thursday.
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NWS forecasters said the frost advisory was in effect until 9 a.m. Thursday, and was due to a dry air mass over the region that dropped temperatures in local areas into the low 30s to upper 20s.
As of 3:50 a.m., 10News Meteorologist Robert Santos said temperatures were still above record lows. But, temperatures dropped another two to three degrees before sunrise.
Temperatures fell rapidly after sunset Wednesday and again on Thursday . Northeast winds from 20 to 30 mph, with occasional 40 mph gusts, were predicted.
Forecasters said the strong winds could have affected area driving, especially for motorists with high profile vehicles. Wind damage to signs, tree limbs and traffic lights was a possibility.
The freezing temperatures could also have damaged or killed sensitive plants.
“ Temperatures this low, while not unheard of in San Diego, are unusual, especially at the coast where the ocean usually has a moderating effect on the mercury," said 10News Meteorologist Pat Brown. "With winter officially beginning on Friday, this weather is a reminder that occasionally winter coats in San Diego are a necessity."