The update said overnight fire behavior was “minimal” as all areas of the fire received rainfall.
“Light and sporadic rain is expected Sunday morning, but by the afternoon and evening, heavy and widespread rain showers are expected. By Monday morning, most fires could receive more than an inch of rain,” the update said.
“The rain changes the firefighting strategy to some extent, but it does not change the priority to improve the conditions in the evacuated areas so that the residents can return.”
The storm system represents an early and significant rain event that experts say could slow down the ongoing fire season — at least temporarily. While this weekend’s rain and cooler temperatures may help contain the fire immediately in the short term, a long-term drought persists across the state.
More rain was expected on Sunday and Monday
The system’s heaviest precipitation is likely Sunday through Monday, when 0.3 inches could fall along the coast and 3 inches over the mountains.
To put the seasonally high rainfall totals into perspective, San Francisco and Sacramento average less than a tenth of an inch of rain in September.
San Francisco last saw rain on August 1st, but it was barely a few hundred inches. It’s been a dry year for the Golden City with only 1.9 inches of rain recorded since January 1, putting the city nearly 11 inches below normal rainfall so far this year.
The last time Sacramento saw measurable rain was more than three months ago on June 5th. They’ve only seen 2.17 inches of rain this year, which is less than about 10 inches, so far.
September is also the third driest month of the year for these cities, behind August and July, as September and October coincide with the peak of fire season in northern and central California.
A Category 1 Excess Precipitation Warning out of 4 has been issued for Sunday for parts of northern and central coastal California, with rainfall rates of up to half an inch per hour possible, which could lead to flash flooding.
“While a lot of precipitation may be beneficial, some isolated runoff problems may occur in urban areas and/or steep terrain,” the Weather Prediction Center said.
A low pressure system is likely to linger along the West Coast early next week, keeping rain chances in the forecast through at least Tuesday.
Rain won’t be the only benefit of this storm. Temperatures will also drop below normal through the weekend, only in the 60s and 70s across much of central and northern California.
Temperatures could be quite cold in the Sierra at elevations above 8,000 feet, with some light snow accumulating Sunday into Monday night.
The unseasonable weather pattern is welcome, but not expected to last long.
The Climate Prediction Center’s 8- and 14-day forecast also shows signs of warmer, drier weather during the last week of September and a return to October.
CNN meteorologists Allison Chinchar and Cheri Mossburg contributed to this report.