Rainbow Flowage Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Rainbow Flowage Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Rainbow Flowage Lake today is 17.4°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 | 18.9°C | 17.9°C | |
| SEP 15 | 18.1°C | 17.9°C | |
| SEP 16 | 18.1°C | 17.9°C | |
| SEP 17 | 18.4°C | 17.9°C | |
| SEP 18 | 17.5°C | 17.9°C | |
| SEP 19 | 18.0°C | 17.9°C | |
| SEP 20 | 18.0°C | 17.9°C | |
| SEP 21 | 17.4°C | 17.9°C | |
| SEP 22 | 17.9°C | 17.4°C | |
| SEP 23 | 17.9°C | 17.5°C | |
| SEP 24 | 17.9°C | 17.5°C | |
| SEP 25 | 17.9°C | 17.5°C | |
| SEP 26 | 17.9°C | 17.5°C | |
| SEP 27 | 17.9°C | 17.6°C | |
| SEP 28 | 17.9°C | 17.6°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 | 0°C | 1°C | 3°C |
| February | 0°C | 1°C | 3°C |
| March | 0°C | 2°C | 5°C |
| April | 1°C | 4°C | 8°C |
| May | 6°C | 12°C | 18°C |
| June | 15°C | 18°C | 22°C |
| July | 18°C | 23°C | 28°C |
| August | 18°C | 24°C | 30°C |
| September | 14°C | 18°C | 22°C |
| October | 9°C | 13°C | 17°C |
| November | 4°C | 9°C | 13°C |
| December | 0°C | 3°C | 6°C |
Rainbow Flowage Lake: Water Temperature by Location
Rainbow Flowage Lake: Weather Forecast
September 21
September 22
September 23
September 24
September 25
Location & Local Information
Rainbow Flowage, a large impoundment in northern Wisconsin, experiences marked seasonal variation in surface water temperature. After ice-out in spring (April–June) surface readings commonly range from about 40–60°F (4–16°C) as the water slowly warms. In midsummer (July–August) sheltered bays and shallow areas often reach the warmest levels, typically between 68–78°F (20–26°C), while open-water and deeper spots may be a few degrees cooler. Temperatures begin to fall in early fall, commonly sliding into the 50–65°F (10–18°C) band by September–November. In winter the lake is usually ice-covered and near the freezing point, roughly 32–36°F (0–2°C), except where currents or springs keep water slightly warmer.
Swimming is generally allowed on Rainbow Flowage because it is public water and commonly used for recreation, but opportunities depend on season and local conditions. The most comfortable and popular time for swimming is summer when surface temperatures exceed about 70°F (21°C); cooler spring and fall waters feel bracing and are less inviting. In winter the ice cover prevents normal swimming, though some individuals practice brief ice dips under controlled, experienced supervision. Swimmers should use designated access points or beaches when available, remain mindful of boat traffic, variable depths and temperatures, and follow local advisories for safety.