Castle Rock Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Castle Rock Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Castle Rock Lake today is 22.3°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature ranges from 68°F (20°C) to 74°F (23°C). The water is warm and pleasant for swimming, and in this range, one can stay in the water for extended periods without the risk of hypothermia. This is the ideal temperature for relaxation, swimming, and water sports. Families with children, as well as outdoor enthusiasts, will enjoy swimming and time spent in the water. For most people, this is the optimal temperature for a comfortable beach experience. 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 | 17.8°C | 24.0°C | |
| AUG 25 | 17.7°C | 24.0°C | |
| AUG 26 | 17.7°C | 24.0°C | |
| AUG 27 | 17.8°C | 24.0°C | |
| AUG 28 | 18.9°C | 24.0°C | |
| AUG 29 | 21.1°C | 24.0°C | |
| AUG 30 | 21.1°C | 24.0°C | |
| AUG 31 | 22.3°C | 24.0°C | |
| SEP 1 | 17.0°C | 22.0°C | |
| SEP 2 | 17.0°C | 21.8°C | |
| SEP 3 | 17.0°C | 21.5°C | |
| SEP 4 | 17.0°C | 21.2°C | |
| SEP 5 | 17.0°C | 21.0°C | |
| SEP 6 | 17.0°C | 20.7°C | |
| SEP 7 | 17.0°C | 20.4°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 | 0°C | 1°C | 3°C |
| February | 0°C | 3°C | 5°C |
| March | 0°C | 2°C | 5°C |
| April | 1°C | 9°C | 16°C |
| May | 7°C | 14°C | 21°C |
| June | 14°C | 18°C | 23°C |
| July | 20°C | 24°C | 29°C |
| August | 17°C | 24°C | 30°C |
| September | 14°C | 17°C | 20°C |
| October | 9°C | 14°C | 19°C |
| November | 2°C | 9°C | 15°C |
| December | 0°C | 2°C | 4°C |
Castle Rock Lake: Water Temperature by Location
Castle Rock Lake: Weather Forecast
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September 6
Location & Local Information
Castle Rock Lake in central Wisconsin experiences a wide range of water temperatures across the year because it is relatively shallow and responds quickly to air temperature. In winter the surface and near-surface water will be near freezing, about 32–39°F (0–4°C) under ice. During spring warming can be brisk, with water commonly in the 40–65°F range (4–18°C) as ice melts and runoff cools the lake. Summer surface temperatures are generally the warmest, often sitting between about 68–82°F (20–28°C) on typical warm days and occasionally reaching the low 80s (around 27–28°C) during heat waves. In autumn the water cools back down, typically falling through the 45–65°F range (7–18°C) before ice forms again.
Swimming at Castle Rock Lake is generally allowed because the lake is a public recreational resource with beaches and access points managed for boating, fishing and swimming. That said, authorities may issue temporary advisories or close areas when water-quality issues arise — most commonly harmful blue‑green algal blooms in warm weather or elevated bacteria levels after heavy runoff — so it’s wise to check local health notices before entering the water. Safety considerations such as boat traffic, variable depths, the absence of lifeguards at many sites, and the usual precautions about not swallowing lake water should also be observed.