Rare Rainstorms Are Shielding San Diego From Wildfires — for Now

Some Bonsall residents had Christmas lights up when the Lilac Fire roared through their community in 2017. The blaze, which started Dec. 7 and wasn’t contained until Dec. 16, destroyed 157 structures and burned 4,100 acres.

That North County inferno, whipped by strong Santa Ana winds and fueled by drought-stricken vegetation, reinforced Cal Fire’s mantra: Wildfire season is now year-round.

Yet an early December repeat this year appears unlikely, thanks in part to this week’s rain. In fact, both locally and statewide, this entire year has been a relatively calm fire period. Firefighters and residents have been given a bit of a reprieve from wildfire angst.

‘We’ve Been Pretty Lucky’

Just three years ago, in 2020, 4.3 million acres burned in California, and 11,116 structures were destroyed. In 2021, the numbers were 2.56 million acres and 3,486 structures. The five-year average has been 1.6 million acres burned. 

This year? Through the end of November, just under 320,000 acres have burned statewide – 20 percent of the recent annual average. The number of structures destroyed has been 52 – less than a third of the total from the 2017 Lilac Fire alone.

“We’ve been pretty lucky,” Cal Fire Capt. Brent Pascua said. “We’re attributing it to a lot of factors. We like to think that that’s due to not only the weather helping out, but to us playing a proactive role and educating the community about defensible space and fuel reduction.”

Prescribed burns, increased use of firefighting aircraft, added staff and resources and technological advances that allow for quicker fire detection and response have also helped, Pascua said.

But there’s no denying weather has been a key element. In the 2022-23 water year, which ended Sept. 30, San Diego recorded more than 150 percent of its normal rainfall, and Palomar Mountain got more than 200 percent of normal. Much of the county and state was similarly wet. 

Plentiful rain means vigorous plant growth, which down the road can become flammable and can cause another set of problems. But Pascua said that while wet years can mean more work for property owners, firefighters prefer them over dry years. Those reduce what they call “fuel moisture” levels of the native vegetation. When plant moisture levels plummet, fires can start more easily and spread quickly.

This year’s rain, which included a big, unusual boost from Tropical Storm Hilary in August, likely helped keep fuel moisture from reaching critical levels. 

But 2022, which was also a relatively mild wildfire year in California (364,000 acres burned), was not nearly as wet. The last two years combined have been the least destructive, in terms of acreage burned, in California since 2010-11.

A Missing Element

Largely missing have been strong wind events, which are often key drivers of massive wildfires, especially in Southern California. There have been Santa Anas this year and there were a few last year, but none compared in intensity or duration to the windstorms of 2003 and 2007, which spread huge wildfires across San Diego County.

The Cedar Fire in 2003 burned 273,000 acres, destroyed more than 2,200 homes and led to 15 deaths. Peak wind gusts around the fire were estimated at 68 mph.

A series of fires in 2007 burned more than 360,000 acres, destroyed roughly 1,600 homes, left 10 people dead and led to evacuation notices for half a million people in the county. Gusts recorded near the Witch Creek Fire in North County reportedly reached 100 mph.

This year, the largest county blaze listed on Cal Fire’s incidents page is the Coyote Fire, at 466 acres on Aug. 17 near the border. Only one other fire all year reached 100 acres: the Bunnie Fire on Aug. 9 near Ramona. That blaze was contained after consuming 184 acres.

“The 2003 and 2007 (winds) were certainly outliers and not something to be expected on a frequent basis,” said meteorologist Samantha Connolly, who works in the National Weather Service Rancho Bernardo office.

Unlike in 2003 and 2007, the weather service has put out very few red-flag warnings in the last two years. The warnings are issued when a combination of high winds, low humidity and dry brush create conditions conducive to rapid fire spread.

There have been fewer strong Santa Ana events (only one this year), and the timing of rainstorms helped keep fuel moisture above critical levels most of last year, Connolly said.

Unless there is a significant warm and dry period that would cause fuel moisture to lower substantially, the fire risk will remain relatively low for the remainder of the rainy season, she said.

“There are some indications that we’ll continue to see periods of rain over the next few weeks, which will continue to mitigate the fire weather threat,” Connolly said. 

Santa Anas are most common in December, but they are rarely as hot as early-season wind events. The fire risk is usually not greatly elevated when the winds arrive after soaking rains. A weak Santa Ana is forecast for the middle of next week. But several San Diego County mountain locations got more than an inch of rain this week, so major impacts are not anticipated. 

San Diego Isn’t Out of the Woods Yet

The state’s Wildfire Forecast and Threat Intelligence Integration Center also shows the fire risk locally is low in the short term, but Pascua doesn’t want homeowners to let their guard down as the calendar advances. 

The Thomas Fire, which burned 281,000 acres and destroyed more than a thousand structures in Ventura and Santa Barbara Counties, started on Dec. 4, 2017. It was not contained until Jan. 12 and is now listed as the ninth largest in state history.

The 2001 Viejas Fire, which burned more than 11,000 acres in eastern San Diego County, was pushed by 65 mph winds. That fire didn’t start until Jan. 3.

Those late-season fires came after prolonged dry periods, and this year has been wetter. But a recent incident shows things could shift rapidly, Pascua said.

The Sage Fire in Jamul on Thanksgiving Day was pushed by 20 mph northeast winds that aligned with the terrain. The blaze quickly turned 39 acres into a moonscape, he said. And that was after a few cool, drizzly days. 

“It’s not going to take weeks of Santa Ana conditions to make things change,” Pascua said.

Longtime backcountry residents who witnessed the 2003 and 2007 fires are not being lulled into complacency by a few fairly benign fire years, Pascua said. 

“I don’t think people forget that easily,” he said. “Residents around San Diego are smart enough to know the danger is still there. But a lot of newcomers that weren’t around, we have to educate them.

“This is just our way of life in San Diego County.” 

November Numbers

Thanks to cool nights, November continued San Diego’s long streak of cooler-than-normal months. The average temperature for the month, measured at the city’s official weather station at San Diego International Airport, was 61.8, or 0.9 of a degree cooler than normal. The average high, 72.8, was 2.1 above normal. The average low was 50.8, which is 4 cooler than normal.

The last month that was warmer than normal in San Diego was October 2022.

Despite this week’s rain, the city has recorded less than half of normal rainfall for early fall. The November total was 0.61 of an inch; normal is 0.79. The total for the season, which began Oct. 1, is 0.62; normal is 1.29. Only 0.01 of an inch fell in October.