It’s Official: September’s Weather Has Been ‘Strange’

Rain is expected to usher in the first day of fall today while unseasonably chilly temperatures persist in a month normally noted for tropical moisture and hot Santa Ana winds.

Scattered showers are not unusual at this time of year, and less than a quarter of an inch of rain is expected to fall in the one-day storm. But the source of the rain and the cool temperatures make this September just plain “strange,” National Weather Service meteorologist Wilbur Shigehara said.

“This weather is very unusual, the flow pattern is more reminiscent of late fall and early winter,” he said.

It is hurricane season, and rain normally arrives from the subtropics at this time of year. Monday’s clouds were generated by now-defunct Hurricane Madeline, which was traveling several hundred miles south of San Diego.

But cool northern air has been funneling down a storm track from Canada, and a low-pressure system that has been clinging to the California coast attracted today’s storm, Shigehara said.

“We don’t have any answer, but this low pressure has made itself felt at home on the West Coast for nearly a month--since the beginning of September. It’s causing the cool temperatures,” he said.

Except for a high of 76 on Sept. 5, September temperatures have been three or more degrees below normal at Lindbergh Field, both day and night.

Monday’s high of 68 at Lindbergh Field was only three degrees above the all-time low temperature for Sept. 22. The normal high is about 76.

Usually September temperatures rise above normal rather than below, and the highest temperature ever recorded in San Diego--111 degrees--was recorded in September, 1963. The high last Sept. 22 was 82 degrees at Lindbergh Field.

“The weather pattern we have now is very unusual, and this September has been a very unusual month. It’s because the jet stream is bringing in cool air, and storms follow the jet stream,” Shigehara said.

Cool temperatures are expected to continue today with scattered showers throughout the county. The National Weather Service received reports of sprinkles Monday afternoon and predicted rain through tonight.

Forecasters said the storm would be brief, however, and some sunshine should break through partly cloudy skies on Wednesday.

It has been dry in San Diego since the last rainfall on July 5. Normal rainfall for September is 0.19 of an inch.