Sullivan Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Sullivan Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Sullivan Lake today is 19.9°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 |
|---|---|---|---|
| JUN 23 | 17.6°C | 20.5°C | |
| JUN 24 | 18.6°C | 20.5°C | |
| JUN 25 | 18.6°C | 20.5°C | |
| JUN 26 | 18.7°C | 20.5°C | |
| JUN 27 | 18.7°C | 20.5°C | |
| JUN 28 | 18.7°C | 20.5°C | |
| JUN 29 | 18.8°C | 20.5°C | |
| JUN 30 | 18.9°C | 20.5°C | |
| JUL 1 | 24.0°C | 20.1°C | |
| JUL 2 | 24.0°C | 20.3°C | |
| JUL 3 | 24.0°C | 20.5°C | |
| JUL 4 | 24.0°C | 20.7°C | |
| JUL 5 | 24.0°C | 20.9°C | |
| JUL 6 | 24.0°C | 21.1°C | |
| JUL 7 | 24.0°C | 21.3°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 | 5°C |
| February | 0°C | 2°C | 5°C |
| March | 0°C | 2°C | 5°C |
| April | 2°C | 6°C | 10°C |
| May | 7°C | 14°C | 21°C |
| June | 14°C | 21°C | 27°C |
| July | 21°C | 24°C | 27°C |
| August | 21°C | 25°C | 28°C |
| September | 17°C | 20°C | 23°C |
| October | 6°C | 13°C | 19°C |
| November | 3°C | 7°C | 11°C |
| December | 1°C | 3°C | 6°C |
Sullivan Lake: Water Temperature by Location
Sullivan Lake: Weather Forecast
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July 4
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July 6
Location & Local Information
Sullivan Lake in Minnesota experiences a wide range of surface water temperatures through the year. In winter months when the lake is iced over, surface temperatures are close to freezing, about 32–36°F (0–2°C). During spring thaw and into late spring, surface temperatures typically rise into the 40–55°F range (4–13°C) as the lake mixes and warms. In the height of summer, shallow areas and surface layers commonly reach comfortable swimming temperatures around 65–75°F (18–24°C), though small, shallow bays can warm a few degrees higher on hot, calm days. In fall the lake cools again, with surface readings usually falling to roughly 45–60°F (7–16°C) as air temperatures drop and turnover begins.
Swimming at Sullivan Lake is commonly done in summer where there is public shoreline access and suitable conditions, because surface waters reach temperatures that most people find pleasant. Whether swimming is allowed at a particular spot depends on property ownership, posted rules, and local ordinances; some shorelines may be private or have restrictions. Swimmers should also consider safety factors: even in summer the water can be much colder below the surface, sudden drops in depth, and occasional algae or water-quality advisories that could limit safe swimming. Always check local access and water-quality information before entering.