Not Like Last Year’s Heat : So Far, August Is Great and It’s Apt to Continue

In contrast to last August’s sweltering heat, cooler than average temperatures this month are expected to hold, with pleasant weather forecast for the weekend.

Daytime temperatures at Lindbergh Field have not topped 75 since Aug. 6, when a 78-degree reading matched the normal temperature for this time of year. Humidity has hovered at an average 65%.

Last August, temperatures in the 80s and 90s at Lindbergh Field, coupled with humidity above 70%, brought a siege of heat that held through record-breaking warm nights. Average nighttime temperatures in the 60s have been the norm this month.

An unusual pattern continues to influence weather in San Diego County, keeping temperatures moderate and slightly below normal.

According to forecaster Wilbur Shigehara, a weak upper-level trough similar to a low-pressure system covers San Diego. When the trough deepens, temperatures drop; when it weakens and becomes shallow, temperatures rise. Thursday’s highs reached near 90 inland, reflecting a temporary thinning of the trough. The trough is expected to deepen through the weekend.

“It’s a variation on a theme we’re looking at,” Shigehara said.

That pattern is rarely seen in August, he said. It is more common in the spring, winter and fall.

High temperatures from 71 to 76 degrees are expected at the beach and along the coastal strip, with coastal lows in the 60s.

Inland valley highs of 76 to 86 degrees are expected to drop to 49 to 59 degrees at night.

Mountain highs should be 77 to 84 degrees, cooling to the 40s and 50s at night. Desert highs of 104 to 108 degrees are expected to fall to 68 to 75 degrees at night.

The remains of tropical storm Marty, which weakened the marine layer and dissipated morning cloud cover at the shore Thursday morning, may continue to push in scattered high clouds through Sunday. Humidity is expected to continue at average levels.

Night and morning cloud cover should be thinner and burn off early for sunny days and some high clouds in all areas of the county through the weekend. West to southwest ocean breezes of up to 20 m.p.h. are expected.