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Is it too cold to swim in Lake Berryessa?
The latest NASA JPL satellite analysis, dated November 3, 2026, gives 64°F (17.6°C) at the nearest water pixel. That is cold water.
Between 60°F and 70°F, which the National Center for Cold Water Safety rates as dangerous. It recommends a wetsuit or drysuit below 70°F. Temperature is only one factor: check rip current and surf alerts, and swim near lifeguards.
How cold is too cold to swim?Water temperature through the year
Average water temperature by month, satellite 2016–2025. Warmest in September.
Average water temperature by month
| Month | Average | Coldest year | Warmest year |
|---|---|---|---|
| January | 52°F | 50°F | 53°F |
| February | 52°F | 48°F | 54°F |
| March | 53°F | 50°F | 55°F |
| April | 54°F | 50°F | 58°F |
| May | 55°F | 49°F | 62°F |
| June | 57°F | 52°F | 66°F |
| July | 59°F | 52°F | 68°F |
| August | 60°F | 54°F | 68°F |
| September | 60°F | 54°F | 67°F |
| October | 58°F | 53°F | 64°F |
| November | 56°F | 52°F | 59°F |
| December | 53°F | 51°F | 55°F |
Water temperatures nearby
Frequently asked questions
Is it too cold to swim in Lake Berryessa?
The latest NASA JPL satellite analysis, dated November 3, 2026, gives 64°F (17.6°C) at the nearest water pixel. That is cold water. Between 60°F and 70°F, which the National Center for Cold Water Safety rates as dangerous. It recommends a wetsuit or drysuit below 70°F. Temperature is only one factor: check rip current and surf alerts, and swim near lifeguards. How cold is too cold?
When is the water warmest at Lake Berryessa?
Based on satellite data from 2016 to 2025, the water is warmest in September (average 60°F) and coldest in January (average 52°F).
Where does this water temperature come from?
We show NASA JPL’s daily MUR satellite analysis for the nearest water, about 0.0 mi away, when no suitable current in-water sensor is available. Satellite values are typically a degree or two cooler than afternoon readings at the shore. Satellite vs. buoy temperatures.
Sources: NASA JPL MUR satellite analysis; forecast and alerts from the National Weather Service. Readings are provisional. All California water temperatures · Methodology