Willow Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Willow Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Willow Reservoir today is 16.5°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 60°F (15°C) to 65°F (18°C). The water is comfortable for most people, making it an ideal range for water sports enthusiasts. The temperature does not cause significant discomfort, and swimming will be pleasant for the majority. However, it's important to remember that prolonged exposure to the water can still lead to cooling, so it's essential to monitor the time spent in the water, especially for children or elderly people. 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 |
|---|---|---|---|
| SEP 14 | 19.0°C | 18.0°C | |
| SEP 15 | 18.2°C | 18.0°C | |
| SEP 16 | 18.1°C | 18.0°C | |
| SEP 17 | 18.5°C | 18.0°C | |
| SEP 18 | 17.3°C | 18.0°C | |
| SEP 19 | 17.9°C | 18.0°C | |
| SEP 20 | 18.0°C | 18.0°C | |
| SEP 21 | 16.5°C | 18.0°C | |
| SEP 22 | 18.0°C | 16.6°C | |
| SEP 23 | 18.0°C | 16.7°C | |
| SEP 24 | 18.0°C | 16.7°C | |
| SEP 25 | 18.0°C | 16.8°C | |
| SEP 26 | 18.0°C | 16.9°C | |
| SEP 27 | 18.0°C | 17.0°C | |
| SEP 28 | 18.0°C | 17.0°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 | 3°C | 6°C |
| March | 0°C | 3°C | 7°C |
| April | 1°C | 5°C | 8°C |
| May | 5°C | 11°C | 18°C |
| June | 15°C | 18°C | 22°C |
| July | 15°C | 22°C | 27°C |
| August | 18°C | 24°C | 30°C |
| September | 14°C | 18°C | 22°C |
| October | 9°C | 14°C | 18°C |
| November | 3°C | 9°C | 14°C |
| December | 0°C | 2°C | 5°C |
Willow Reservoir: Water Temperature by Location
Willow Reservoir: Weather Forecast
September 21
September 22
September 23
September 24
September 25
Location & Local Information
Willow Reservoir in Wisconsin experiences pronounced seasonal shifts in water temperature typical of northern reservoirs. In summer the surface often warms to roughly 68–78°F (20–26°C), making the upper layers comfortable for short swims on warm days, while deeper water remains much cooler, often in the 40–55°F (4–13°C) range because of thermal stratification. Spring and fall are transition seasons: spring surface temperatures commonly rise from the mid-30s–50s°F (2–13°C) as ice melts and the water mixes, and fall sees cooling back through the 50s–60s°F (10–16°C) before overturn. In winter the reservoir is usually at or near freezing at the surface (about 32°F/0°C) under ice, while water below the ice stays just above freezing.
Swimming opportunities at Willow Reservoir are generally available in suitable, designated recreation areas, but access and allowed activities depend on local regulations, land ownership, and posted signage. Even when permitted, swimmers should be mindful of cold-water risks from deep, cool layers, boat traffic, variable shoreline conditions, and changing water levels. For safety and current rules it’s advisable to consult local authorities or the managing agency before planning to swim.