Large Scale Summary
- Support for troughs focusing 130-145W. The main governing agent is the MJO with a maximum along about 165-175W.
- Precipitation Amounts and Fire Risk: A wet period with Atmospheric Rivers (AR) and heavy rainfall with higher than usual snow levels in ORWA(Oregon-Washington) during mid Nov 12-14,17, Dec 12-15.
- Central and S California preliminary rain dates of Dec 12-15.
Near Term Forecast
NORCAL
- PRECIPITATION DATES: Nov 13-14, 20, 23-25, 26-30, Dec 3.
- COLD/FREEZES/WINDS: Nov 19-21, 25-27 windy
- WARM/DRY PERIODS: NOV 16-18
- MOUNTAIN SNOWS: NOV 22-23,25-29
CENTRAL CALIFORNIA
- PRECIPITATION DATES: Nov 13-14, 20, 23-25, 26-30, Dec 3
- COLD/FREEZES/WINDS: Nov 13-14, 19-21, 25-27 windy, 28-29 freezes
- WARM/DRY PERIODS NOV 16-18. 21-22
- MOUNTAIN SNOWS: NOV 14, 23, 25-29
SOUTHERN CALIFORNIA
- PRECIPITATION DATES: Nov 13-14, 20, 23-25, Dec 3
- COLD/SANTA ANA WINDS: 14-15, 19-21, 26-28 windy, 28-30 freezes
- WARM/DRY PERIODS: NOV 16-18. 21-22
- MOUNTAIN SNOWS: Nov 14,18, 23-25, 28
SOUTHERN CALIFORNIA DESERTS
- PRECIPITATION DATES: NOV 19, 23-25
- COLD/N-NE WINDS: 13-14, 19-21, 26-28 windy, 28-30 freezes
- WARM/DRY PERIODS: Nov 16, 18, 25
- MOUNTAIN SNOWS: Nov 13-14, 28-flurries
Medium Term Outlook: Dec 11 — Dec 31
NORCAL
- PRECIPITATION DATES: ,DEC 13,14-16, 25-27.
- COLD/FREEZES/WINDS: Dec 20-22,28-31
- WARM/DRY PERIODS: Dec 23-24
- MOUNTAIN SNOWS: Dec 16-18, 25-28
CENTRAL CALIFORNIA
- PRECIPITATION DATES: DEC 13,14-16, 25-27
- COLD/FREEZES/WINDS: Dec 20-22,28-31.
- WARM/DRY PERIODS: Dec 21-23, 24-25.
- MOUNTAIN SNOWS: Dec 16-18, 26-31
SOUTHERN CALIFORNIA
- PRECIPITATION DATES: DEC 13,14-16,26-27
- COLD/SANTA ANA WINDS: 19-21, 28-30
- WARM/DRY PERIODS: Dec 22-25,31
- MOUNTAIN SNOWS: Dec 16, 18
SOUTHERN CALIFORNIA DESERTS
- PRECIPITATION DATES: DEC 13,14, 25-27,30
- COLD/N-NE WINDS: Dec 19-21, 28-31
- WARM/DRY PERIODS: Dec 22- 24
- MOUNTAIN SNOWS: Dec 16, 18
DISCUSSION OF NOAA/NCEP/CPC MAPS JAN-FEB 2026
- The latest guidance from NOAA/NCEP/NWS/CPC suggests that Dec 2025 remains mostly dry through mid Dec, as in Nov. Sometime near the 20 Dec or between 12/23/25-01/01/26, it turns wet, as we often see around the holidays. The main wet months are November 2025 and January 2026, with focus of significant rains from about Sacramento Delta south to SOCAL. Above average snow levels are currently indicated for the NORCAL mountains and Sierras, and for SOCAL mountains. That scenario is consistent with potential for Atmospheric River (AR) systems in Jan for most areas of California, except the North Coast.
- With the current expansion of La Nina, there appears to be less support for subtropical westerlies to continue through the months of Dec-Feb. The latest CFSv2 information for Feb 2026 shows a possible pause in the rains, with below average rain amounts for California, but with above average amounts for Washington and Oregon. The signal we are seeing for this La Nina period is not consistent. Nov appears wet, but Dec and Jan are inconsistent for the CFSv2 model. Feb appears to trend to near average, but trends for rainfall in Feb and Mar are dependent upon trends earlier in the winter.
A Few Comments on the Larger Picture and La Nina
- Here in mid Nov there is indication of an expanding areal coverage of La Nina, both into the southern tropical Pacific as well as north tropical Pacific, bordering Hawaii. The La Nina pattern as of 11 Nov 2025, has expanded east to the Peruvian coast south through central Chile. North of the equator, La Nina remains centered in the central and west portions from 120W out to the Dateline. However, La Nina has been increasing as we approach the middle of the El Nino-Southern Oscillation (ENSO). There is also anomalously warm sea surface (positive SSTA pattern) from Hawaii to Baja California, and California.
The SSTA pattern in the midlatitude N Pacific west of California still supports some troughing in the areas affecting NORCAL to Oregon-Washington (ORWA) regions. We certainly see the effects of this is the rain anomalies (positive) for Nov 2025, and Jan 2026. - Despite La Nina, central California is not persistently dry throughthe normal rainy months of Nov - Mar. There is certainly support for some extended dry months during that period. We see the wet biases as mentioned for Nov 2025 and Jan 2026, and possibly support for some wet bursts in mid season.
Figures and Text: Alan Fox, Fox Weather, LLC
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