Water Year in Review (so far): A Tale of Surges and Stalls
In California, even an “average” water year is rarely linear. Water Year 2024-25 unfolded as a sequence of surges and stalls—early precipitation, dry periods, and rebounds. We can see these patterns reflected in the 8, 6, and 5-station indices.
The Northern Sierra, San Joaquin, and Tulare Basin precipitation indices for Water Year (WY) 2024–25 alongside two analog years are shown below. The pink band highlights the month of April. Precipitation came in below average across the board: 2.5” in the Northern Sierra (58% of average), 2.2” in the San Joaquin (63%), and 1.8” in the Tulare Basin (72%).
The drying trend became more pronounced in May. The Northern Sierra managed just 0.8” (28% of average), the San Joaquin 0.2” (9%), and the Tulare Basin 0.1” (7%). With the exception of the San Joaquin, current traces for WY 2025 continue to track between the analog years 2017–18 and 2018–19.
The chart below tells the month-by-month water year story, with each line showing observed precipitation as a percentage of monthly average. While each basin followed a slightly different path, all three shared a few defining traits: a strong November, a historically dry January, and a February surge.
Northern Sierra (blue line in chart)
Despite an incredibly dry January (just 12% of average), this region banked early-season water with a blowout November (254%) and February (187%). March maintained at 102% of average, but April and May slowed considerably—just 58% and 28%, respectively. As of June 4, this region is at 103% of normal for the full water year.
San Joaquin (orange)
This region never fully recovered from January’s near-shutdown (9%). Even with a healthy February (120%) and decent March (93%), the spring couldn’t pick up the slack: April brought just 62% of average and May delivered only 9%. As of June 4, the region is sitting at 26.3”, 66% of water year average.
Tulare Basin (green)
The southernmost basin in the index trio followed a similar arc. After a dry January (9%), February and March came in strong—149% and 140%, respectively. April delivered 72% of normal, and May just 7%. The current total is 22.8" against a seasonal norm of 28.3”, representing ~81% of water year normal.
Approximate Statewide WY Totals
According to CWW data through 06/02/2025, statewide precipitation sits at approximately 91% of WY normal. This year the Core Supply region has run 2–3% wetter than the state as a whole, placing it around 93.5%, comfortably within CAP’s projected range of 90–110%.
CRAFT Update: A Forecast That Holds
Water managers are familiar with the cadence of spring inflow forecasts: DWR’s Bulletin 120 (B-120) updates begin arriving in February, adjusting as snowpack, temperature, and runoff patterns evolve. But CRAFT is issued once—in November—and isn't adjusted.
The chart below shows how both approaches have played out over the course of WY 2024-25 for Lake Shasta. The B-120 forecast range (orange bars) began in February with a wide spread of 4.38 million acre-feet, and narrowed each month as conditions clarified. By contrast, CRAFT (light blue band) provided a fixed range from the beginning: 1.575 million acre-feet, issued in November and never adjusted.
The green line shows observed inflow through late May, now settling within the CRAFT range, even with its four-month head start and without any mid-season adjustment. While the B-120 tracked conditions more responsively, CRAFT gave water managers a long lead time, and is expected to verify.
This stability isn’t a coincidence. It reflects the strength of the CAP-based forecast at the core of CRAFT: a precipitation outlook that accurately captured statewide conditions again this year.