Since our previous outlook, the region saw a couple of decent storms in the second half of February, followed by drier conditions in March. A cold storm in mid February brought a fair amount of lower-elevation snow to the Sierra. This was followed by a much warmer storm in late February that affected mainly only the northern half of the region.
Other than the first week of March, temperatures have been above average since the last storm in late February. Temperature anomalies over the next several days are expected to be even higher than we’ve seen over the past few weeks. Higher-elevation temperatures are expected to be > 20°F above average Tue through Sat across the region. Temperatures are expected to exceed the record max temperatures in the 45-year climatology period, and low temperatures are forecast to exceed average high temperatures at times this week. This will continue the trend of increased snowmelt.
Figure 1 - Percent of average precipitation for Feb 2026 (top) and Mar 1-15, 2026 (bottom). Source: CNRFC
Figure 2 - Time series of basin-averaged temperature for two basins in the Sierra
Basin | Feb 15 (Before storms) | Feb 21 (After cold storm) | Feb 26 (After warm storm) | March 15 (Today) | March 25 (Forecast) |
NFDC1 (American R) | 32% | 72% | 71% | 41% | 21% |
FRAC1 (San Joaquin R) | 65% | 104% | 93% | 59% | 35% |
Table 1 - CNRFC modeled SWE % of average
As shown above and in Figure 3 below, peak SWE across the Sierra occurred in late February, and SWE has shown a steady decline since then. With melt increasing in March, some seasonal runoff is being shifted earlier and occurring prior to the typical “April-July” snowmelt period. This, along with below-average precipitation in March, is contributing to declining April-July volume accumulation forecasts (Figure 4 below), with forecast April July runoff declining from 97% of average in mid February to 54% of average today.
Figure 3 - CA snow water content by region. Source: CA Department of Water Resources
Figure 4 - April-July 2026 runoff forecast trend for the Central Valley Water Supply Index
Similar to the seasonal forecasts, water year forecasts have shown a similar overall downward trend over the past month or so thanks to the lack of significant precipitation since late February (Figure 5).
Figure 5 - Water Year 2026 runoff forecast trend for the Central Valley Water Supply Index
As discussed earlier and shown in Figure 2, well-above-average temperatures are expected over the next several days. In addition, no precipitation is expected across the CNRFC forecast area for the next 6 days (not shown). CPC outlooks for March 22-28 show near to slightly below-normal precipitation and continue to strongly favor above-normal temperatures across the region. The outlook for March 28-April 10 leans toward below-average precipitation in northern CA and equal chance of above- or below-average precipitation elsewhere, while the temperature forecast continues to lean above normal.
Figure 6 - Precipitation (top) and temperature (bottom) outlooks for March 22-28. Image source: CNRFC Data source: CPC
Figure 7 - Precipitation (top) and temperature (bottom) outlooks for March 28-April 10. Source: CPC
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