As Northern California braces for a potent late-November storm system, NOAA has issued a clear warning: above-normal precipitation is expected from November 29 to December 5, 2025, with heavy rain and significant snowfall looming over the Sierra Nevada. The forecast, released on November 21, 2025, comes after a soaking start to the month—Northern California has already received over 3 inches of rain this November, more than two inches above average. By October 1, the water year’s total had climbed to 5 inches, nearly 3 inches ahead of normal. This isn’t just a wet spell—it’s a pattern, and it’s building toward a climax.
Storms Build as Thanksgiving Approaches
The timeline is precise: San Francisco will see light rain by Wednesday night, November 26, followed by heavier, widespread precipitation Thursday afternoon, November 27—Thanksgiving Day. Los Angeles won’t escape unscathed, with rain arriving later that same day. The San Jose area, meanwhile, has already endured 3 to 8 rainy days this month, with total rainfall hitting 39 millimeters and morning fog becoming a daily nuisance for commuters. Temperatures remain mild but deceptive: highs hover near 65°F, but overnight lows dip into the 40s, making wet roads and chilly air a dangerous combo.Travelers on I-5 are being warned: showers will intensify early next week, with the highest risk on November 26–27. The National Weather Service is already flagging potential flash flooding in low-lying areas, especially near creeks and drainage channels that have been saturated for weeks. "It’s not just the rain—it’s the ground can’t take any more," said one local hydrologist, speaking anonymously. "We’re already at 85% of our November capacity. One more big system and we’re looking at overflow.""
Sierra Snow: A Double-Edged Sword
While the valleys drown in rain, the Sierra Nevada will be dusted with snow—potentially 1 to 3 feet at elevations above 7,000 feet. That’s good news for ski resorts like Lake Tahoe, which have struggled with low snowpack in recent years. But it’s also a logistical nightmare. Caltrans has already pre-positioned plows and sanding trucks along key passes, including Donner Pass and Ebbetts Pass. Snow chains may be mandatory by Friday, December 5, as the system stalls over the mountains."We’ve had three storms already this month," said a spokesperson for the California Department of Water Resources. "This next one could be the tipping point for snowpack accumulation. If we get consistent snow above 8,000 feet, we could close the gap on last year’s deficit by 30% in a single week.""
Uncertainty Lingers in the Models
Despite the clear trend, meteorologists are cautious. "There’s a lot of models going back and forth," said a NOAA forecaster during a November 21 broadcast. "Some show the system stalling over Northern California for days. Others push it offshore sooner." The uncertainty isn’t just academic—it affects emergency planning. Schools, hospitals, and local governments are on alert but holding off on full-scale shutdowns until the model consensus sharpens.What’s clear is that the active weather pattern won’t end with December 5. The same forecast noted that by Friday, December 5, the system could begin breaking down, potentially extending wet conditions into the weekend of December 6–7. Southern California, meanwhile, may see a delayed but still significant pulse of rain, keeping the entire state in a state of hydrological tension.
Why This Matters Beyond the Rain Gauge
This isn’t just about soggy shoes and canceled picnics. Northern California’s reservoirs—Shasta Lake, Lake Oroville, and Folsom Lake—are still operating below 60% capacity despite the recent rains. A strong snowpack in the Sierras is the region’s best hope for a stable water supply through next summer. But too much rain too fast could trigger landslides in fire-scarred hillsides from the 2020 and 2021 wildfires. The USGS has already issued landslide advisories for parts of Sonoma, Napa, and El Dorado counties.For farmers in the Central Valley, the timing is critical. Winter crops like almonds and walnuts need moisture, but standing water can rot roots. And for the 1.2 million residents of the Bay Area, the risk of power outages from downed trees and wind gusts is rising. Pacific Gas and Electric has deployed extra crews, but grid stress remains high.
What’s Next? Watch the Mountains
The next 72 hours will be decisive. If the system lingers and dumps snow above 8,000 feet, California could be looking at its best snowpack start since 2019. If it races through, the state may face another dry spell by mid-December, setting up a repeat of last year’s "whiplash" pattern—wet then dry, then wet again.Residents are advised to check emergency kits, clear gutters, and avoid driving through flooded roads. The NOAA outlook doesn’t guarantee disaster—but it does guarantee preparation. In a state where water is power, and snow is life, this storm isn’t just weather. It’s a test.
Frequently Asked Questions
How much rain is Northern California expected to get during the Nov 29–Dec 5 storm window?
NOAA forecasts 3 to 6 inches of rain across the northern valleys, with higher totals—up to 8 inches—in coastal ranges and foothills. The Sierra Nevada could receive 10 to 20 inches of snow above 7,000 feet, significantly boosting snowpack levels. This would push the region’s November rainfall total to nearly 6 inches, nearly double the historical average.
Is this storm related to El Niño?
While not officially declared, current oceanic conditions in the Pacific strongly suggest a developing El Niño pattern, which typically enhances storm tracks toward California. Sea surface temperatures off the coast are 2–3°F above average, a key indicator. If confirmed, this storm sequence could be the first of several powerful systems expected through winter, potentially bringing the state closer to normal water levels after years of drought.
What are the biggest risks to public safety?
The primary risks are flash flooding in recently burned areas, mudslides in steep terrain, and hazardous driving conditions on mountain passes. Power outages are also likely due to wind gusts up to 40 mph combined with saturated soil that makes trees easier to uproot. Emergency services are urging residents to avoid travel unless necessary, especially through the Sierra Nevada between Friday and Sunday.
How does this compare to last year’s weather pattern?
Last November, Northern California received only 0.8 inches of rain—far below average. This year’s total of over 3 inches by November 21 is more than triple that. The water year (since October 1) is also significantly ahead: 5 inches so far versus just 1.7 inches at this time last year. If the forecast holds, 2025 could mark the first time since 2019 that the state enters winter with above-average reservoir levels.
Will this end California’s drought?
Not yet. One wet month doesn’t erase five years of deficit. But if the Sierra snowpack reaches 120% of average by January, and additional storms follow in January and February, California could fully recover its water reserves by spring. The key is sustained moisture—not just a single storm. The state’s water managers are cautiously optimistic but still urging conservation.
What should residents do to prepare?
Check emergency kits for flashlights, batteries, and non-perishable food. Clear gutters and downspouts. Avoid camping or hiking in fire-scarred areas. If you live in a flood-prone zone, know your evacuation route. And if you’re heading to the mountains, carry chains, a full tank of gas, and warm clothing—even if you’re just driving through. The weather is turning serious, and preparation saves lives.
