The discussion that follows pertains to the California Annual Precipitation (CAP) forecast. For information on our inflow product, the California Reservoir Annual Forecast Tool (CRAFT), navigate to “CRAFT Forecasts” on the left sidebar.

Core Supply Dashboard

WY 2025-26 Precipitation Forecast: Above Normal, Decreasing to the South

Following an “average” year in 2024-25, it looks like much of California will experience above average precipitation in water year 2025-26, with a drying gradient to the south.

The California Annual Precipitation (CAP) forecast indicates that water year precipitation will be 105-125% of normal for at least the northern half of the Sacramento Valley.
The San Francisco Bay area and latitudes from Wheatland to Modesto fall within the range from 100-120% of WY normal.
The northern San Joaquin Valley is forecast to receive between 92.5 and 112.5% of WY normal precipitation and the southern San Joaquin Valley looks positioned to receive between 87.5 and 107.5% of WY normal.

For more details by region, see the Regional section below. For an in-depth forecast discussion, see the Insights section on the left sidebar.

Returning customers will notice that this year’s forecast includes a new level of geographic detail and granularity. This improvement reflects our ongoing investment in expanding the Weather Tools Station network. Our work is not finished; more stations will be deployed after the wet season to deliver even more localized insight going forward.

The dashboard below shows the Core Supply status (Regions 2, 4, and 6, shaded blue) with observed data through October 31, 2025.

Core Supply:
CAP Forecast WY 2025-26

Core Supply: Year-over-Year Comparison

Highlights

In the CAP data record, weak La Niña years have been associated with varied precipitation patterns for the Core Supply region: above-normal precipitation occurred twice (in WY 2016-17 with 71.4% above normal and WY 2022-23 with 37.7% above normal) and below-normal precipitation twice (in WY 2017-18 and WY 2021-22, with deficits of 20.4% and 22.6%, respectively) and near-normal totals in 2024-25 (95% of normal). Despite these varied outcomes, CAP consistently verified.
Within our nine-year CAP record, water years 2018-19 (Weak El Niño) and WY 2024-25 (Weak La Niña) have key model indices that align most closely with the present year (see accumulation curves below). For the Core Supply region, precipitation in WY 2018-19 was 28% above normal and WY 2024-25 was 95% of normal. We expect WY 2025-26 to fall between the two. We will be closely monitoring these analog years as the season progresses.