Sweetwater Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Sweetwater Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Sweetwater Reservoir today is 31.7°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature is above 82°F (28°C). This is very warm water, which may feel almost hot to most people. Swimming in such conditions is perfect for those seeking relaxation and comfort in the water. These waters are often preferred for relaxation in hot weather, as the water temperature does not cool the body significantly. However, it is important to remember that in such warm waters, caution is necessary, as prolonged exposure without rest can lead to overheating. 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 |
|---|---|---|---|
| AUG 24 | 29.9°C | 30.2°C | |
| AUG 25 | 29.7°C | 30.2°C | |
| AUG 26 | 29.7°C | 30.2°C | |
| AUG 27 | 32.0°C | 30.2°C | |
| AUG 28 | 31.7°C | 30.2°C | |
| AUG 29 | 31.7°C | 30.2°C | |
| AUG 30 | 31.8°C | 30.2°C | |
| AUG 31 | 31.7°C | 30.2°C | |
| SEP 1 | 29.0°C | 31.6°C | |
| SEP 2 | 29.0°C | 31.4°C | |
| SEP 3 | 29.0°C | 31.3°C | |
| SEP 4 | 29.0°C | 31.2°C | |
| SEP 5 | 29.0°C | 31.0°C | |
| SEP 6 | 29.0°C | 30.9°C | |
| SEP 7 | 29.0°C | 30.8°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 | 14°C | 19°C | 24°C |
| February | 14°C | 20°C | 25°C |
| March | 15°C | 20°C | 25°C |
| April | 17°C | 23°C | 29°C |
| May | 20°C | 25°C | 29°C |
| June | 23°C | 26°C | 29°C |
| July | 25°C | 30°C | 34°C |
| August | 27°C | 30°C | 34°C |
| September | 26°C | 29°C | 32°C |
| October | 23°C | 25°C | 27°C |
| November | 17°C | 22°C | 26°C |
| December | 16°C | 20°C | 23°C |
Sweetwater Reservoir: Water Temperature by Location
Sweetwater Reservoir: Weather Forecast
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Location & Local Information
Sweetwater Reservoir in San Diego County tends to have cool, seasonally variable surface temperatures. Typical winter surface readings fall in the low 50s °F (around 10–14 °C), spring warms into the mid‑50s to mid‑60s °F (about 13–18 °C), and summer surface temperatures frequently reach the mid‑60s to low‑to‑mid‑70s °F (roughly 18–24 °C). In late summer under prolonged heat the very surface can occasionally climb a few degrees higher. Deeper water remains noticeably colder year‑round, and the reservoir can show thermal stratification so that bottom temperatures stay lower than surface values.
Swimming in Sweetwater Reservoir is generally not permitted because it is managed as a municipal water supply and authorities prohibit contact recreation to protect public health and the drinking water system. Restrictions are also motivated by safety concerns—steep banks, submerged hazards, and variable water quality, including occasional algal activity, make unsupervised swimming risky. Visitors can still enjoy shoreline trails and regulated recreational uses consistent with Sweetwater Authority rules, but direct contact with the reservoir water is limited to protect both swimmers and the water supply.