Diamond Valley Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Diamond Valley Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Diamond Valley Lake today is 30.4°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 |
|---|---|---|---|
| JUL 14 | 25.9°C | 25.6°C | |
| JUL 15 | 28.1°C | 25.6°C | |
| JUL 16 | 28.3°C | 25.6°C | |
| JUL 17 | 28.5°C | 25.6°C | |
| JUL 18 | 28.5°C | 25.6°C | |
| JUL 19 | 28.5°C | 25.6°C | |
| JUL 20 | 28.5°C | 25.6°C | |
| JUL 21 | 30.2°C | 25.6°C | |
| JUL 22 | 25.6°C | 30.2°C | |
| JUL 23 | 25.6°C | 29.9°C | |
| JUL 24 | 25.6°C | 29.7°C | |
| JUL 25 | 25.6°C | 29.4°C | |
| JUL 26 | 25.6°C | 29.2°C | |
| JUL 27 | 25.6°C | 29.0°C | |
| JUL 28 | 25.6°C | 28.7°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 | 10°C | 13°C | 17°C |
| February | 8°C | 12°C | 17°C |
| March | 9°C | 15°C | 21°C |
| April | 15°C | 18°C | 22°C |
| May | 16°C | 20°C | 25°C |
| June | 19°C | 24°C | 28°C |
| July | 21°C | 26°C | 31°C |
| August | 23°C | 26°C | 28°C |
| September | 21°C | 24°C | 27°C |
| October | 20°C | 23°C | 25°C |
| November | 15°C | 20°C | 25°C |
| December | 12°C | 16°C | 20°C |
Diamond Valley Lake: Water Temperature by Location
Diamond Valley Lake: Weather Forecast
July 22
July 23
July 24
July 25
July 26
Location & Local Information
Diamond Valley Lake is a large, deep reservoir in Southern California whose surface water warms noticeably in summer but remains cool compared with coastal swimming spots. Seasonal surface temperatures typically run about 50–60°F (10–16°C) in winter, rise to roughly 55–65°F (13–18°C) in spring, reach about 70–80°F (21–27°C) — occasionally touching the low 80s (around 27–28°C) — in the warmest summer months, and fall back to roughly 60–75°F (16–24°C) in autumn. Because the lake is quite deep, thermal stratification is common: deeper layers can remain much colder year‑round, often in the 40–55°F range (4–13°C), which increases drowning and hypothermia risk for unprepared swimmers.
Swimming and wading at Diamond Valley Lake are not allowed. The prohibition is primarily to protect water quality in a municipal water supply reservoir and to reduce safety hazards associated with steep drop‑offs, cold deep water, and boat traffic. Recreational activities such as fishing, boating, and picnicking are available in designated areas under management rules, but direct contact with the water is restricted to preserve public health and the integrity of the water system.