Castaic Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Castaic Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Castaic Lake today is 30.7°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 4 | 31.2°C | 27.6°C | |
| AUG 5 | 31.1°C | 27.6°C | |
| AUG 6 | 31.1°C | 27.6°C | |
| AUG 7 | 31.2°C | 27.6°C | |
| AUG 8 | 31.2°C | 27.6°C | |
| AUG 9 | 31.2°C | 27.6°C | |
| AUG 10 | 31.3°C | 27.6°C | |
| AUG 11 | 30.7°C | 27.6°C | |
| AUG 12 | 27.6°C | 30.5°C | |
| AUG 13 | 27.6°C | 30.4°C | |
| AUG 14 | 27.6°C | 30.2°C | |
| AUG 15 | 27.6°C | 30.1°C | |
| AUG 16 | 27.6°C | 29.9°C | |
| AUG 17 | 27.6°C | 29.8°C | |
| AUG 18 | 27.6°C | 29.6°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 | 11°C | 13°C | 16°C |
| February | 9°C | 12°C | 16°C |
| March | 8°C | 14°C | 20°C |
| April | 13°C | 17°C | 21°C |
| May | 18°C | 22°C | 26°C |
| June | 19°C | 23°C | 27°C |
| July | 22°C | 26°C | 30°C |
| August | 24°C | 28°C | 32°C |
| September | 22°C | 24°C | 27°C |
| October | 21°C | 24°C | 26°C |
| November | 16°C | 21°C | 24°C |
| December | 13°C | 17°C | 19°C |
Castaic Lake: Water Temperature by Location
Castaic Lake: Weather Forecast
August 12
August 13
August 14
August 15
Location & Local Information
Castaic Lake, a managed reservoir in Southern California, shows noticeable seasonal variation in surface water temperature. In winter the lake is cool, typically around 50–58°F (10–14°C). Spring sees a steady warming with surface temperatures often ranging from about 55–68°F (13–20°C) as air temperatures rise. During summer the shallow surface can warm considerably, commonly reaching roughly 68–78°F (20–26°C) on warm days, though deeper areas remain cooler. In autumn temperatures generally fall back into the 60–72°F (16–22°C) range as the lake begins to cool toward winter. These values are approximate and depend on recent weather, water levels and depth, but they highlight why the lake feels brisk outside the peak summer months.
Swimming is permitted only in designated areas and during times when lifeguards and park staff allow it; much of the reservoir is focused on boating, fishing and water storage so open swimming across the lake is discouraged or restricted for safety. Restrictions reflect hazards such as boat traffic, sudden depth changes, cold temperatures below the surface, and water-quality or reservoir-management concerns. If you plan to swim, use the designated swim zone when staffed, heed posted rules, and check current park advisories for closures or temperature-related cautions.