Fire danger is expected to be high across San Diego County from Wednesday night through Friday as moderate Santa Ana winds and single-digit humidity levels blow into the region.
The National Weather Service has issued a red flag warning from 11 p.m. Wednesday until 5 p.m. Thursday for the county's inland and mountain areas, where winds are expected to gust from 30 mph to 70 mph.
Temperatures on Wednesday are expected to hover in the low 70s at the beach and 83 inland. On Thursday, daytime highs are expected to jump 10 degrees higher.
Humidity levels are expected to dip as low as 5 percent in some inland regions.
“The drop in relative humidity will further dry local vegetation and combine with gusty winds to increase the potential for wildfire ignition and spread,” National Weather Service forecasters warned.
With springtime green hills already brown and dry, firefighters are bracing for a dangerous fire season. Cal Fire officials increased staffing and equipment, including fire engines, bulldozers and air tankers.
In a Facebook post, Cal Fire urged residents to be extra vigilant.
![San Diego County is expected to be warmer than average through the summer, according to the U.S. Climate Prediction Center as of April 15, 2015.](https://cdn.kpbs.org/dims4/default/e00b430/2147483647/strip/true/crop/595x366+0+91/resize/880x542!/quality/90/?url=http%3A%2F%2Fkpbs-brightspot.s3.us-west-2.amazonaws.com%2Fimg%2Fphotos%2F2015%2F04%2F15%2Foutlook.png)
“During these times, extreme caution is urged by all residents because a simple spark can cause a major wildfire," the post said.
Rainfall at San Diego's Lindbergh Field since Jan. 1 is 5 inches below normal. The four-year rainfall deficit has grown to 17 inches, said Alex Tardy, a National Weather Service meteorologist.
Hot and dry conditions are expected to continue through spring and summer, according to a U.S. Climate Prediction Center report.