San Joaquin River at Vernalis, CA
River level and flood forecast · San Joaquin County
The river is 20.5 ft below flood stage (29 ft).
Forecast to rise to 9.1 ft Sat 5 AM, below the 29 ft flood stage.
Flow: 1,320 cubic feet per second (USGS).
The last 7 days and the forecast
NWS forecast issued Mon, Oct 12, 7:45 AM. Forecasts change as rain falls and as upstream water arrives.
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An email when the National Weather Service forecasts San Joaquin River at Vernalis to flood, when it floods, and when it's over.
Flood stages
| Major flood stage | 37.3 ft |
| Moderate flood stage | 32 ft |
| Flood stage | 29 ft |
| Action stage | 24.5 ft |
| Record crest (January 5, 1997) | 34.88 ft |
What floods at each level
From the National Weather Service, highest first.
- 37.29 ftStages above 37.3 feet results in flooding outside the levees. Top of levee.
- 29.6 ftHomes along east bank of river on Airport Court in Manteca experience flooding.
- 26 ftSevere seepage occurs outside the levees. The area covered by seepage will increase as the river stage rises.
- 24.5 ftMonitor Stage - water reaches the toe of levee.
- 21 ftSeepage begins into crop area outside of levees.
Highest crests on record
- 34.88 ft — January 5, 1997
- 32.81 ft — December 9, 1950
- 30.72 ft — February 23, 2017
- 29.83 ft — March 19, 2023
- 29.8 ft — March 18, 1986
Recent crests: 16.01 ft (February 21, 2026) · 13.03 ft (March 20, 2025) · 18.12 ft (March 6, 2024) · 29.83 ft (March 19, 2023) · 25.7 ft (January 18, 2023)
Up and down the river, and nearby
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (VNSC1); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.