National Weather Service California Nevada River Forecast Center Department of Commerce National Oceanic and Atmospheric Administration National Weather Service

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SAN JOAQUIN RIVER - VERNALIS (VNSC1)
Latitude: 37.68º NLongitude: 121.27º WElevation: 35 Feet
Location: San Joaquin County in CaliforniaBulletin Group: San JoaquinRiver Group: San Joaquin
Issuance Time: Apr 30 2025 at 7:37 AM PDTNext Issuance: May 01 2025 at 9:00 AM PDT
Action/Monitor: 24.5 FeetMinor Flood: 29.0 FeetModerate Flood: 32.0 FeetMajor Flood: 37.3 Feet

Please Note:
1) Each individual timeseries plotted on the graphical river forecast can be toggled on and off by clicking the legend entry above. If the "Observed (Raw Data)" contains bad data and is toggled off, the plot will scale to the remaining timeseries.

2) At extremely low river flows, the "Observed (Raw Data)" may show readings below the lower end of the available rating table, while the "Observed (Simulated)" will only show values at the bottom of the rating table, creating a potential discrepancy between the two readings.
Observed Data Credit
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Raw streamflow data is provided by the US Geological Survey (USGS).
View US Geological Survey (USGS) Data for this station location.

Verification - Historical Graphical RVF
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To view other verification locations, use our Historical Graphical River Forecast Interface.
Historical Stage/Flow Data
Water Year
Peak Discharge (cfs)
Stage (feet)
Date
 Most Recent 5 Years
2024*
10,300
18.12
Mar 6, 2024
2023*
34,400
29.82
Mar 19, 2023
2022*
2,600
10.83
Dec 29, 2021
2021*
2,470
10.76
Jan 31, 2021
2020*
6,130
14.29
Dec 9, 2019
 Historical High Stage/Flow Events (Period of Record - Jul 1922 to Present) - Ranked by Flow
1951*
79,000
27.75
Dec 09, 1950
1997*
75,600
34.88
Jan 05, 1997
1969*
52,600
34.55
Jan 27, 1969
1938*
51,200
26.64
Mar 16, 1938
1956*
50,900
26.89
Dec 25, 1955
1983*
45,100
31.49
Mar 07, 1983
 * Discharge affected by regulation or diversion
Location Photographs
ESRI™ Locator Map
Flood Impacts
37.29 FeetStages above 37.3 feet results in flooding outside the levees. Top of levee.
29.6 FeetHomes along east bank of river on Airport Court in Manteca experience flooding.
26.0 FeetSevere seepage occurs outside the levees. The area covered by seepage will increase as the river stage rises.
24.5 FeetMonitor Stage - water reaches the toe of levee.
21.0 FeetSeepage begins into crop area outside of levees.
Official 7 Day National Weather Service Forecast   (CAZ019)
Today: Sunny. Highs 78 to 86. Northwest winds up to 10 mph.

Tonight: Clear. Lows 49 to 57. Northwest winds up to 10 mph.

Friday: Sunny. Highs 74 to 83. Northwest winds up to 10 mph. Gusts up to 20 mph in the afternoon.

Friday Night: Clear in the evening then becoming mostly cloudy. Lows 50 to 56. West winds up to 15 mph with gusts to around 30 mph.

Saturday: Mostly cloudy in the morning then becoming mostly sunny. Highs 64 to 74. West winds up to 15 mph with gusts to around 30 mph.

Saturday Night: Mostly clear. Lows 47 to 54.

Sunday: Mostly sunny. Highs 68 to 78.

Sunday Night: Mostly clear. Lows 49 to 55.

Monday through Wednesday: Clear. Highs 76 to 86. Lows 49 to 58.
Product Disclaimer

This river graphic is not intended to serve as a substitute for official flood watches, warnings, advisories, or statements issued by the NWS Sacramento Weather Forecast Office. Observations are preliminary and subject to change. River levels identified as "forecast" should be consistent with those contained in official NWS products. River levels identified as "guidance" have significant uncertainty due to future weather or reservoir regulation and are provided for planning purposes only.