Lake Mendota — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Mendota, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Mendota today is 23°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 4 | 23.7°C | 22.0°C | |
| AUG 5 | 23.6°C | 22.0°C | |
| AUG 6 | 22.6°C | 22.0°C | |
| AUG 7 | 22.5°C | 22.0°C | |
| AUG 8 | 22.6°C | 22.0°C | |
| AUG 9 | 22.7°C | 22.0°C | |
| AUG 10 | 22.8°C | 22.0°C | |
| AUG 11 | 23.0°C | 22.0°C | |
| AUG 12 | 22.0°C | 23.0°C | |
| AUG 13 | 22.0°C | 22.9°C | |
| AUG 14 | 22.0°C | 22.9°C | |
| AUG 15 | 22.0°C | 22.8°C | |
| AUG 16 | 22.0°C | 22.8°C | |
| AUG 17 | 22.0°C | 22.7°C | |
| AUG 18 | 22.0°C | 22.7°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 | 1°C | 3°C | 6°C |
| March | 2°C | 6°C | 9°C |
| April | 4°C | 9°C | 14°C |
| May | 10°C | 14°C | 19°C |
| June | 13°C | 18°C | 23°C |
| July | 17°C | 24°C | 30°C |
| August | 17°C | 22°C | 27°C |
| September | 15°C | 19°C | 22°C |
| October | 9°C | 14°C | 18°C |
| November | 2°C | 7°C | 11°C |
| December | 0°C | 3°C | 6°C |
Lake Mendota: Water Temperature by Location
Lake Mendota: Weather Forecast
August 12
August 13
August 14
August 15
Location & Local Information
Lake Mendota, the northernmost of Madison’s four lakes, experiences wide seasonal variation in surface water temperature. In winter the lake typically hovers near freezing, around 32–39°F (0–4°C) under ice cover. Spring brings a steady warm-up, with surface temperatures commonly in the 40–60°F range (4–16°C) as stratification begins. By mid to late summer the surface often reaches roughly 68–82°F (20–28°C), and during heat waves can climb into the mid-80s°F (around 29°C). In autumn the surface cools again, generally falling through the 50s into the 40s°F (10–4°C) before refreezing; deeper water remains considerably colder year-round.
Swimming in Lake Mendota is allowed at designated beaches and parks and is a popular recreational activity in summer because surface temperatures are usually comfortable for bathing. Local agencies routinely monitor water quality and post advisories; occasional nuisance or toxic blue‑green algal blooms and bacterial spikes can lead to temporary closures for health reasons. Even when open, swimmers should be mindful of variable temperatures near shore and at depth, possible currents, and changing conditions, and they should follow posted guidance and any lifeguard instructions for safety.