Big Saint Germain Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Big Saint Germain Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Big Saint Germain Lake today is 20.5°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 | 21.2°C | 24.0°C | |
| AUG 25 | 21.0°C | 24.0°C | |
| AUG 26 | 20.7°C | 24.0°C | |
| AUG 27 | 20.7°C | 24.0°C | |
| AUG 28 | 20.9°C | 24.0°C | |
| AUG 29 | 21.8°C | 24.0°C | |
| AUG 30 | 21.8°C | 24.0°C | |
| AUG 31 | 20.4°C | 24.0°C | |
| SEP 1 | 16.1°C | 20.3°C | |
| SEP 2 | 16.1°C | 20.1°C | |
| SEP 3 | 16.1°C | 19.8°C | |
| SEP 4 | 16.1°C | 19.6°C | |
| SEP 5 | 16.1°C | 19.4°C | |
| SEP 6 | 16.1°C | 19.2°C | |
| SEP 7 | 16.1°C | 19.0°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 | 0°C | 2°C | 4°C |
| February | 0°C | 1°C | 3°C |
| March | 0°C | 3°C | 6°C |
| April | 1°C | 4°C | 7°C |
| May | 6°C | 12°C | 18°C |
| June | 15°C | 18°C | 22°C |
| July | 16°C | 22°C | 27°C |
| August | 18°C | 24°C | 30°C |
| September | 14°C | 16°C | 19°C |
| October | 9°C | 13°C | 17°C |
| November | 4°C | 9°C | 13°C |
| December | 0°C | 3°C | 6°C |
Big Saint Germain Lake: Water Temperature by Location
Big Saint Germain Lake: Weather Forecast
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September 6
Location & Local Information
Big Saint Germain Lake in northern Wisconsin typically follows the seasonal temperature pattern common to midwestern lakes. In spring surface temperatures often rise from roughly 40–60°F (4–16°C) as ice melts and the water stratifies. Summer brings the warmest conditions, with surface temperatures commonly reaching about 68–78°F (20–26°C) in July and August on warm afternoons; shallow bays can be a few degrees warmer. By early fall the surface cools back toward 50–60°F (10–16°C) and by late fall and winter the lake approaches near-freezing conditions, with water under ice generally around 32–39°F (0–4°C).
Swimming is generally allowed and is a popular summer activity at shoreline properties, resorts and public access points, because summer temperatures are suitable for recreational use and many areas are managed for safe access. Local rules, posted advisories and water-quality reports should be checked before entering the water, and lifeguard availability varies by site. Winter swimming or ice swimming is possible only with proper safety measures and is uncommon; during freeze-over the ice and near-surface water are cold enough to present hypothermia risks, so standard summer swimming practices do not apply.