The autumn heat wave sweeping San Diego County will continue through the end of the week with a couple of additions: a Flex Alert Thursday and a red flag warning Friday.
NBC 7’s Ashley Matthews said in the First Alert Forecast Thursday that San Diego’s inland areas will see temperatures around 100 degrees and low humidity – a recipe for those fire-prone conditions that Southern California knows all too well.
“We’re going to be seeing temperatures 10 to 20 degrees above normal during this time,” Matthew said. “It increases fire danger as well we’re seeing very dry conditions – and gusty winds, especially tonight.”
Matthews said the Santa Ana winds coupled with low humidity were expected to peak Friday morning.
“That’s not a good combination, so we have to be very careful,” she added.
California's Flex Alert
Due to the weather conditions, the California Independent System Operator (ISO) issued a statewide Flex Alert – a call for California residents to voluntarily conserve energy – from 3 p.m. to 10 p.m. Thursday.
The ISO said the unseasonably hot conditions will lead to increased electricity demand late in the day, putting strain on the state’s grid.
Ahead of the Flex Alert, the ISO said Californians should “pre-cool” their homes and buildings by setting air conditioning thermostats lower than usual. Once the alert kicks in, thermostats should be set at 78 degrees or higher to help conserve energy. You can get more energy conservation tips from the agency on the ISO website.
The ISO has issued similar Flex Alerts over the past few months during heat waves across the state.
Fire Weather Warning
The National Weather Service said a fire weather warning – or red flag warning – would go into effect for parts of Southern California on Friday, from 3 a.m. to 6 p.m., for gusty winds and low humidity.
The coastal slopes of the San Bernardino County and Santa Ana Mountains would be impacted by the warning, as well as the San Gorgonio Pass near Banning, California.
The NWS said north to northeast winds were expected to reach 20 to 30 mph, with possible gusts up to 40 mph. The agency said the strongest gusts – 40 to 50 mph – were expected below the region’s Cajon Pass.
Humidity would fall between 5 and 8% Friday, too, the NWS said.
Under these extreme fire behavior conditions, any fires that spark can and will spread quickly, the NWS warned.
The winds were expected to weaken by Friday evening, which is when the 4-day heat advisory that San Diego County has been under will expire. The heat advisory started at 11 a.m. Tuesday and will expire at 5 p.m. Friday.
Matthews said that while there will be “sunshine everywhere” in San Diego County over the next 10 days, temperatures will normalize for this time of year by next week.
San Diego Knows About Fire Weather in October
Hot, dry weather in October is nothing new for San Diego. The conditions this time of year can sometimes create risky fire weather; this happened in October 2003 with the devastating Cedar Fire and in October 2007 with the Witch Fire.
California’s 2020 wildfire season has been one for the history books. Since the beginning of the year, more than 8,400 wildfires in the state have scorched more than 4 million acres, according the California Department of Forestry and Fire Protection. There have been 31 deaths related to California’s 2020 wildfires and more than 9,200 buildings have been destroyed.
Last month, the August Complex in the Coast Range between San Francisco and Oregon became California’s largest wildfire on record.
And now with the October heat, firefighters warn that California’s deadly wildfire season may not be over.
As of Oct. 8, more than 13,800 firefighters remained on the lines of 21 major wildfires across the state, Cal Fire said.
Just this past September, the Valley Fire scorched more than 16,000 acres near Alpine in San Diego’s East County.
With October’s reputation for California wildfires and this week’s heat advisory for the region, firefighters in San Diego County are on high alert, Isaac Sanchez with Cal Fire said.
Sanchez said the memories of the 2003 Cedar Fire are vivid and the lessons learned in that firefight are still used by crews to prepare for fire weather today.
“[It’s] the single significant event here in San Diego County,” Sanchez told NBC 7. “The event that we look back on and we compare to today. And when we do that, we do that with a sense of dread, of course.”
The fire season window that once typically ran from May to October in San Diego County now appears to be getting longer, possibly through as late as December.
“It’s hotter for longer periods of time, it’s dryer for longer periods of time and, of course, that wetting rain that we’re typically used to just isn’t coming like it used to come,” Sanchez explained.
But Sanchez said Cal Fire has adapted to the changes and is more prepared than ever.
Cal Fire has increased staffing and equipment, upgrading aircraft fleets like helicopters and, in the future, an airtanker.
“We are growing with the threat,” he said. “But it is a very real threat that the rest of the community and, of course, the rest of the agencies, that we all have to take very seriously.”