Data Note: NWS Correction and Additional Data Source

A significant error in National Weather Service (NWS) record-keeping related to average water year precipitation has recently been identified. This affected the normals used in WY percentage calculations and resulted in slightly inflated values.

The NWS indicates that this issue has now been corrected. As a result of these adjustments, current water year percentages may appear slightly lower than expected given recent precipitation.

To provide additional context, we are also referencing water year totals from Golden Gate Weather (GG, hereafter). These values are derived from a different set of NWS station observations and processed through a separate archival system. This provides an independent calculation of water year totals and allows for cross-comparison with NWS-issued values.

We are monitoring this update closely and are taking care to ensure that our reporting reflects the most accurate and consistent data available.

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. Water Year inflow numbers have been updated through January 31, 2026.

The discussion that follows pertains to the ALICE model forecast for California. For information on our inflow product, the California Reservoir Annual Forecast Tool (CRAFT), navigate to “CRAFT Forecasts” on the left sidebar where Water Year inflow numbers have been updated through April 27, 2026.

View the initial 2025–26 water year forecast.

View Forecast Release

Core Supply Dashboard

WY 2025–26 Precipitation Forecast: Near Normal Overall, Slightly Wetter in the North

Following an “average” year in 2024–25, precipitation for water year 2025–26 is projected to be near normal across California. Forecast guidance suggests a modest north–south gradient, with conditions trending near to slightly above average in the northern portion of the Core Supply region and near to slightly-below average in the south.

See the Regional Sections for a more detailed breakdown by region.

The dashboard below shows the Core Supply status (Regions 2, 4, and 6, shaded orange) with observed data through April 27, 2026.

Core Supply:
CAP Forecast WY 2025-26

Highlights

April made up for what March lacked. According to NWS totals, the Core Supply received an impressive 4.92 inches of accumulation, increasing water year progress by approximately 15 percentage points.
With the Core Supply currently at 91% of average based on NWS data and 95.6% using GG Weather, conditions sit just below or at the lower bound of the ALICE forecast range.
NWS precipitation totals reflect broader water supply conditions, while GG Weather values highlight conditions in valley and coastal areas and in situ recharge. Visit the Regional Pages to explore conditions most relevant to your operations.
With April’s precipitation boost, the accumulation curves are tracking closely with those of analog years 2018-19 and 2024-25. See the Insights Section for accompanying graphics and a comprehensive discussion of precipitation through the end of April.
Please note, observed reservoir inflows through April 27, 2026, are available in the CRAFT section of the portal.

Latest Insight

April 30, 2026

Monthly Update: A Shift in the Precipitation Pattern

March brought the season to a near standstill, with precipitation accumulation flat-lined across much of California during what is typically one of the wetter months of the year. April reversed that trend. Rather than tapering off—as is more common this time of year—the pattern turned active, delivering steady gains and re-accelerating water year progress across the state.

So how wet was April in a historical context? The answer depends on where you look.