San Luis Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in San Luis Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in San Luis Reservoir today is 18.5°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming. It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Water Temperature Chart Over the Last 30 Days
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| OCT 26 | 19.8°C | 21.0°C | |
| OCT 27 | 20.5°C | 21.0°C | |
| OCT 28 | 20.4°C | 21.0°C | |
| OCT 29 | 19.5°C | 21.0°C | |
| OCT 30 | 19.2°C | 21.0°C | |
| OCT 31 | 19.8°C | 21.0°C | |
| NOV 1 | 19.4°C | 17.0°C | |
| NOV 2 | 18.5°C | 17.0°C | |
| NOV 3 | 17.0°C | 18.4°C | |
| NOV 4 | 17.0°C | 18.4°C | |
| NOV 5 | 17.0°C | 18.3°C | |
| NOV 6 | 17.0°C | 18.2°C | |
| NOV 7 | 17.0°C | 18.1°C | |
| NOV 8 | 17.0°C | 18.1°C | |
| NOV 9 | 17.0°C | 18.0°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 9°C | 12°C | 14°C |
| February | 9°C | 11°C | 14°C |
| March | 6°C | 13°C | 20°C |
| April | 13°C | 16°C | 20°C |
| May | 14°C | 19°C | 25°C |
| June | 17°C | 21°C | 26°C |
| July | 18°C | 23°C | 29°C |
| August | 21°C | 26°C | 31°C |
| September | 19°C | 23°C | 27°C |
| October | 17°C | 21°C | 25°C |
| November | 12°C | 17°C | 21°C |
| December | 10°C | 14°C | 17°C |
San Luis Reservoir: Water Temperature by Location
San Luis Reservoir: Weather Forecast
November 3
November 4
November 5
November 6
November 7
Location & Local Information
San Luis Reservoir, a large inland reservoir in central California, experiences noticeable seasonal shifts in surface water temperature. In summer months the surface commonly ranges from about 65–80°F (18–27°C), making short swims more tolerable; spring and fall temperatures are typically cooler, roughly 50–70°F (10–21°C) depending on weather and recent inflows. During winter the surface often drops into the 40–55°F (4–13°C) range. Because the reservoir is deep, colder thermocline water sits below the warmer surface layer, so temperatures can fall quickly with even brief dives or in deeper spots.
Swimming at San Luis Reservoir is subject to park rules and safety considerations rather than a blanket prohibition; recreation is managed through the State Recreation Area and visitors must follow posted signs and any seasonal restrictions. Safety concerns — including cold-water shock and rapid temperature changes, steep banks, submerged structures, boat traffic and sometimes limited lifeguard coverage — mean swimming is advised only in designated or supervised areas and with caution. Water quality and access can vary, so checking current park guidance before entering the water is recommended.