McMahon Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in McMahon Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in McMahon Lake today is 18.7°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming. 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 | 20.9°C | 21.2°C | |
| SEP 15 | 20.5°C | 21.2°C | |
| SEP 16 | 19.6°C | 21.2°C | |
| SEP 17 | 18.4°C | 21.2°C | |
| SEP 18 | 18.5°C | 21.2°C | |
| SEP 19 | 18.4°C | 21.2°C | |
| SEP 20 | 18.6°C | 21.2°C | |
| SEP 21 | 18.7°C | 21.2°C | |
| SEP 22 | 21.2°C | 18.8°C | |
| SEP 23 | 21.2°C | 19.0°C | |
| SEP 24 | 21.2°C | 19.1°C | |
| SEP 25 | 21.2°C | 19.2°C | |
| SEP 26 | 21.2°C | 19.3°C | |
| SEP 27 | 21.2°C | 19.5°C | |
| SEP 28 | 21.2°C | 19.6°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 | 3°C | 7°C |
| February | 0°C | 3°C | 6°C |
| March | 0°C | 4°C | 9°C |
| April | 4°C | 9°C | 15°C |
| May | 11°C | 17°C | 22°C |
| June | 17°C | 22°C | 27°C |
| July | 22°C | 25°C | 29°C |
| August | 20°C | 24°C | 28°C |
| September | 18°C | 21°C | 25°C |
| October | 6°C | 13°C | 19°C |
| November | 3°C | 7°C | 11°C |
| December | 1°C | 5°C | 8°C |
McMahon Lake: Water Temperature by Location
McMahon Lake: Weather Forecast
September 21
September 22
September 23
September 24
September 25
September 26
Location & Local Information
McMahon Lake, like many small lakes in Minnesota, experiences pronounced seasonal shifts in surface water temperature. Through the winter months the surface is typically at or near freezing around 32°F (0°C) under ice, with the water directly below the ice often in the low 30s to upper 30s °F (0–4°C). During spring turnover temperatures commonly rise from about 40–60°F (4–16°C) as the lake warms, and in summer the open-water surface usually ranges from roughly 68–78°F (20–26°C), with shallow bays sometimes reaching the low to mid 80s °F (27–29°C) on hot afternoons. In autumn the lake cools again, dropping through the 50s to near 40°F (10–4°C) before ice formation.
Swimming at McMahon Lake is generally practical and commonly enjoyed in the warmer months when surface temperatures are in the comfortable 68–78°F (20–26°C) range, provided there is public access and no local restrictions. Whether swimming is officially allowed depends on shoreline ownership, posted signage, and current water-quality conditions; advisories for blue‑green algae blooms or unsafe bacterial counts can lead authorities to recommend avoiding water contact. As with any Minnesota lake, swimmers should check local notices, be mindful of cooler deep-water temperatures that increase hypothermia risk, and use standard safety precautions.