• Less than half an inch of rain is expected Saturday through Monday.
• Landslide risk near recent burns is low, but threat cannot be ruled out.
Amid firestorms and extended red flag warnings, the idea of weekend rain is a balm for the Southern California soul. More rain will help put out the fires, but forecasters say it won't end the devastating fire season.
The rain will “bring very beneficial rain” but “will not end the fire season,” said National Weather Service meteorologist Alex Tardy.
Ryan Kittell with the NWS noted that with less rain expected, there is less risk of debris flows in burned areas. But chances of extinguishing the fire season are also slim.
“If we get a little more dry weather, it will negate any of the benefits of this rain,” meteorologist Kittel said.
That dry weather may be just around the corner. The long-term outlook suggests further weeks of dry weather on the heels of this storm.
“Not very likely,” Kittel said, “and we're looking at drier conditions this weekend, possibly into early February.”
Light rain is likely
Forecasters are hoping for some rain and mountain snow this weekend. They also expect less than half an inch of rain for the three-day rain event from Saturday to Monday.
The forecast is likely to bring half an inch to San Diego, San Clemente and Covina; two-fifths from downtown Los Angeles and Long Beach; a third of an inch for Anaheim, Redondo Beach and San Clemente; and a quarter inch for Santa Clarita and Canoga Park.
If those totals are correct, they would snap a record dry streak for the city of Los Angeles. It's been 262 days since downtown LA saw more than a tenth of an inch of rain in a single day — and that was on May 5.
Before this Feb. From 25 to 3 November 2008, the record was 253 consecutive days.
Downtown LA has had almost no rain since the water year began on October 1st. Only 0.16 inches of rain has fallen since then — one of the driest starts to a water year on record. Only 3% of downtown's average rainfall accumulates at this point in the water year, which is 6.19 inches. For the entire water year, Downtown LA averages 14.25 inches of rain.
Across Southern California, this is the driest start to the water year.
“We have never been in this area before. We've never seen a mid-January with these numbers. Never,” said Weather Service meteorologist Tardy. Rainfall and Santa Ana winds — five wind events this month alone — make for a brutal combination.
The predicted timing and totals of the upcoming rain event are still uncertain, Kittel noted. Light rain or an inch in some places. Rain is possible anytime Saturday through Monday, but the best chance is Saturday night through Sunday morning.
Slight chance of thunderstorms and landslides
There is a 10% to 20% chance of thunderstorms, along with an isolated, but brief, chance of heavy rain.
As a result, there is a small chance of landslides, debris flows and mudslides near recently burned areas, Kittel said.
“Heavy rain, approaching half an inch per hour,” Kittel said, along with thunderstorms.
“Most areas won't see this type of situation,” he added, but if there are thunderstorms, “most likely we'll see one place — or two or three — get conditions like this.”
“It's not an atmospheric river,” Tardi said. “It's a cold storm. It's good for our burns.”
There is a risk of small hail across the region, Kittel said. At 3,500 to 4,500 feet above sea level, snow levels decrease. Ski resorts in Southern California could get up to 10 inches of snow, Tardi said.
There is a possibility that a thunderstorm will directly emerge in the recently burned area – creating a landslide hazard – but it is unlikely.
“It's a possibility, but the risk is low,” Kittel said. Still, “it's something to think about.”
In recently burned areas, he said, the rains serve as a practice to prepare for potential hazards for the next year or two, after which the risk of debris flows and other landslide hazards is significantly reduced.
Recently burned areas are at risk of landslides if subjected to heavy rainfall in a short period of time.
Hillsides are prone to landslides after wildfires because fires drive water out of the soil, and instead of being absorbed, rain flows downhill and picks up rock and debris.
“Landslide” is an all-encompassing term that can describe any downward movement of rock, dirt, or debris. There are different types of landslides, including mudslides, in which water flows only with mud, usually less than 15 feet deep.
During a debris flow, the water flowing rapidly downstream not only picks up mud, but also rocks, branches, trees, and sometimes boulders. It is considered a type of shallow landslide.
Garbage flows are dangerous. In January 2018, 23 people died It also destroyed at least 130 homes as a river of mud and rock flowed through coastal Montecito, which burned a month earlier in the Thomas Fire.
Rainfall rates should be a half-inch per hour or more, which makes the debris important, Kittel said. Lower rates — such as a quarter-inch per hour — are less significant, he said, adding that “some roads may move some muddy water.”
Before the rain comes more fire weather
Meanwhile, Red Flag Fire Weather Warnings — which began Monday morning across Southern California — will continue for much of Southern California through Thursday night. A red flag warning is likely to be extended for windy areas until Friday.

A red flag warning will remain in place for large swaths of Southern California through Thursday night.
(National Weather Service)
The wind was very strong earlier this week. Along the Magic Mountain truck route, winds gusted to 88 mph Monday morning in the western San Gabriel Mountains, said Lisa Phillips, a meteorologist with the weather service.
In the mountains east of San Diego, wind gusts reached 102 mph at Chill Hill, Feb. 26, close to the all-time record of 105 miles set on 2020, Tardi said.
Winds will be light from the northeast for most of Wednesday. But they will expand and strengthen Wednesday night into Thursday morning, and begin to taper off Thursday night, Kittel said.
Air is forecast to be very dry with humidity below 10% until Friday. The meteorologist warned that the vegetation is very dry and there is a risk of fire if it catches fire.
“Even though there are areas that don't have a lot of wind, the faster fire growth and the greater fire danger — it's just too big,” Kittel said. “And put any wind on it, it just makes it worse.”

(National Weather Service)
Peak winds of 30 to 50 mph are expected in Los Angeles and Ventura counties Wednesday afternoon through Thursday night. Wind gusts of 50 mph to 65 mph are possible in the mountains and foothills.
Peaks at 30 mph in Oxnard and Anaheim, 33 mph in the western San Fernando Valley, 36 mph in Mira Mesa, 37 mph in Fillmore, 39 mph in Escondido, 40 mph in Thousand Oaks, 43 mph in Santa Clarita, and 43 mph in 47 It can be windy. , 54 mph in Ramona and 55 mph in Beaumont.

(National Weather Service)
As of Tuesday afternoon, the weather service did not plan to upgrade the red flag warnings for “particularly hazardous conditions” later this week.
“Even if you don't have PDS, a red flag warning for this is still a significant event,” Kittel emphasized.
“This is certainly not a situation where we let our guard down.”