Temperature Cooled Off by Ocean Breezes

Cooling sea breezes that ended a four-day siege of heat and brought relief to San Diego County for Thursday’s Independence Day holiday are expected to restore seasonal weather through the weekend.

Temperatures throughout the county, which dipped slightly on Wednesday, plunged 10 degrees or more on Thursday when a coastal eddy generated low clouds and a surge of moist marine air.

Winds circulating in the miniature low pressure system offshore blew in higher humidity and clouds from the southwest, creating overcast skies at most southern beaches and promoting hazy sunshine along the North County shore and the inland valleys, the National Weather Service reported.

The high of 73--the average temperature for a July 4--at Lindbergh Field on Thursday was 15 degrees below Wednesday’s high and equal to Sunday night’s low .

Temperatures that had simmered in the 90- to 110-degree range inland fell to the 80s in most areas on the holiday. The high in La Mesa dropped 23 degrees to 80, and temperatures fell to 89 in Escondido, 81 at Montgomery Field, 86 in El Cajon, 80 at San Diego State University and 87 in Santee.

Although cooler weather along the coastal strip eased fears of fire in San Diego, outlying brush areas remained on a red-flag alert status called by the state Department of Forestry.

According to CDF fire spokeswoman Audrey Hagen, the fire hazard inland remains high. “It is still a red alert--everything is so dry it wouldn’t take much.”

August Ghio, dispatch captain for the San Diego Fire Department, said the fire hazard had decreased sufficiently by Thursday to allow the number of firefighters and engines automatically dispatched to fires to be reduced from the highest of alert categories to lower levels.

Smog concentrations also declined to normal patterns as the high pressure system shifted, allowing the low pressure to gain influence. Pollution levels that had been measured unhealthful by the Air Pollution Control District this week in communities near the coast fell dramatically Thursday.

Per the norm, good air quality was evident downtown and in Chula Vista, Del Mar, La Mesa and Oceanside. In Alpine, on the other hand, air became unhealthful as ocean breezes carried the pollutants inland to jump the count to 125 on the Pollutant Standard Index.

Although smog levels are expected to increase slightly today, air quality will continue favorable.

Humidity returned to seasonal levels along the coast with 90% in the early morning and 60% in the afternoon.

Night and morning low clouds and fog are expected at the beach through the weekend with high temperatures from 68 to 74. The ocean temperature was 67 degrees at Mission Beach on Thursday.

Highs along the coastal strip of 70 to 76 degrees will cool to the 60s at night through Sunday, forecasters said. Farther inland, temperatures are expected in the 79- to 89-degree range, with lows at night from 58 to 64.

Breezes are expected in the mountains and deserts, where sub-tropical clouds may arrive to increase humidity.

Mountain highs will be 82 to 90, falling to 57 to 65 at night. Deserts will top out at 102 to 110, with overnight lows in the 70s.