Pressure Is On, Bringing Humidity and Sprinkles

A 30% chance of showers or thundershowers is forecast through Monday as moisture continues to pour in from Mexico, according to the National Weather Service in San Diego.

Competing weather systems of high and low pressure are funneling the moisture up from northern Mexico, forecaster Gordon Hepburn said. The movement of moist air out of Mexico is typical of summer, he said.

The pull of the air northward is caused by a high-pressure system situated over Four Corners--the area where Arizona, Utah, Colorado and New Mexico meet--and low pressure off Baja California, Hepburn said.

The moisture drove the humidity at Lindbergh Field up to 90% on Saturday and brought 0.01 of an inch of rain by 4 p.m., he said.

Most other areas received just traces, but measurable rainfall was recorded at Brown Field and Cuyamaca Rancho State Park, each of which received 0.02 of an inch, and Spring Valley, which received 0.01 of an inch.

The rainfall was the first for the rain season, which runs from July 1 to June 30. Last season had recorded none by this date.

Temperatures on Saturday ranged from a low of 66 degrees at Coronado and Oceanside Harbor to a high of 96 at Borrego Springs.

Other temperatures recorded were: 74 degrees at Lindbergh Field; 73 in Del Mar; 84 in Escondido; 87 in Fallbrook; 86 in Julian; 79 in Lemon Grove; 80 in Miramar; 72 at Montgomery Field; 86 in Poway; 83 in Ramona; 90 in Santee; 76 in Spring Valley and 83 in Vista.

Temperatures failed to go higher because of a persistent cloud cover, Hepburn said. Skies will remain partly cloudy today, with temperatures at the beaches of 66 to 72 today and Monday. The surf is rolling in at 1 to 2 feet, and the ocean temperature is about 66 degrees.

Coastal temperatures will range from 72 to 80 today and Monday, with lows of 60 to 65. Inland areas will have highs of 80 to 90 and lows of 57 to 62 through Monday.

Mountain temperatures will rise to 78 to 88 today and Monday, falling to 54 to 62 at night. The mercury in the deserts will climb to 95 to 105 today and Monday, falling to 77 to 87 both nights.