Large Scale Summary
- Focus of rains in Nov occur Nov 1. Rain volume will mitigate Fire Spread Risk, and the airmasses while unstable, will be more consistently moist with enough showery
periods to maintain a moist fuels in most fire prone areas of Central and N California, and for Oct 21-27 in SOCAL. For Nov: rains focus 1-2, 5 Nov and 11-17 Nov, both in NORCAL and in the Sierras. Depending on how much rain occurs, the risk for wildland fires diminish at times, mainly in late Oct and early and mid Nov. - In Dec and Jan, the general guidance currently available suggests more consistent rains through mid to late Dec, throughout the state in Jan, and in NORCALcoast to Siskiyouís in Feb. It may become difficult to transition into wetter conditons until mid to late Oct and Nov, when the tropical cyclone season finally comes to an end.
- In the fall, including mid fall, certainly lightning and wind are important influencers of autumn fire weather. So, even if some wet periods occur, presence of lightning/
TSTMS and gusty/fickle winds are still risk factors to consider, even in a wet fall. - Bands of showers associated with upper lows and rains, can easily develop severe weather situations. This includes mergers with other other nearby rain-bands, and
create their own problems regarding fire development.
PRECIPITATION DATES
- NORCAL/North California Sierras: Nov 10, 12, 15-24, 26, 28, 29, 30, Dec 1.
- NORCAL NE Plateau, N Sierra: Nov 11, 12-20, 22, 24, 25, 28, 29, 30, Dec 1.
- Tahoe Donner: Nov 10, 11,1 2-23, 24, 28, 29, 30, Dec 1.
- Yosemite NP: Nov 12-23, 24, 28, 29, 30, Dec 1.
- Sequoia/Kings: Nov 12-16, 20-21, 24-25, 28, 29, 30, Dec 1.
- N Sacramento Valley Nov 10,11,12-15,16,17,18,19, 20, 22, 24, 26-Dec 1.
- N San Joaquin Valley/Delta: Nov 12-16, 20, 21, 24, 25, 28-Dec 1.
- Santa Clara Co 11-20,24,28,29,30,Dec1.
- Monterey Co 13,14,15,16,20,24,28-Dec 1.
- SOCAL
- San Luis Obpo Co and Edna Vly 15,16,20,24,25,28-Dec 1.
- Santa Barbara Co 15,16,20,24,25,28-Dec 1.
- Ventura Co west 15,20,24,25,28-Dec 1.
- Ventura Co east 15,20,24,25,28-Dec 1.
- East LA Co. 15,20,21,25,Dec 1.
- Orange Co. 15,20,21,25,Dec 1.
- Riverside Co west 15,20,21,25,Dec 1.
- Riverside Co east DESERTS 21,25,Dec 1.
- San Bdno Mtns 15,20,21,Dec 1.
- E San Bdno Mtns Oak Glen Watershed 15,20,21,Dec 1.
- OAK GLEN WATERSHED: Forest Falls 15,20,21,Dec 1.
- San Diego Co - coast & beaches 15,20,25,Dec 1.
- San Diego Co Inland Empire 15,20,21,25,Dec 1.
- CUYAMACA State Park 15,20,21,25,Dec 1.
- SOUTHERN DESERTS 21,25,Dec1
EXTENDED FORECAST
- Rains in Nov per the NOAA outlook maps appear to be in early Nov before the mid Nov rains begin around 10th and onward in Nov. Currently the rains in Nov appear to be from landfalling lows and cold fronts. Some of these fronts ingest tropical moisture from the Nino3.4 region. Beginning about mid Nov, and and recurring in Dec
and Jan, per the NOAA NCEP 1 month outlook maps also included at the endof this report. In Nov and Dec, the heavier rains appear to begin, and focus through in a few incidents thru most of northern and central California. Focus of heaviest rains continues from mid Dec into January 2027. Dec 2026 most of Jan 2027 appear to be the wettest periods. - December 2026 rainfall well above average for N, Central, and above average for S California. Possibility exists for only short breaks between significant rains.
- The Jan 2027 Outlook maps for rain in Jan and Feb from NOAA should still be taken seriously. There still appears enough support for possible flash flood in mid Dec through Jan 2027.
- Warm oceanic mesoscale eddy patterns, plus unusually warm SSTAs (Synoptic Anomalous Warm Ocean Surface SAWOS and Oceanic Heat Index (SAWOS/OHI) are good physical indicators for rain probability and amount.
- As we transition to mid-fall (late Oct-Nov), there may be a few more interactions between tropical moisture and energetic troughs/upper lows in the westerlies and subtropical regions.
- The latest guidance from NOAA/NCEP/CPC is suggesting that the heaviest rains are in January, while the rain amounts will tend to decrease in Feb and Mar 2027. In Apr 2027, the precipitation anomaly appears to go negative, i.e. below average precipitation. There will be a period after the middle of January, and in February, when the mean monthly temperatures will drop well below average, resulting in a good snowfall in the mountains and Plateau areas. Interestingly, although precipitation amounts drop to near average in Feb and Mar, the cold airmasses will tend to produce the coldest and snowiest storms of the winter.
- El Nino is present in the equatorial region (Nino 3.4 region) 130W ñ 165W.about 130W to Hawaii at 160W to near 170W).
Figures and Text: Alan Fox, Fox Weather, LLC
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