Roy Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Roy Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Roy Lake today is 4.6°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
❌ As of today, the minimum water temperature ranges less than 41°F (5°C). Such water is extremely cold and not recommended for swimming without proper preparation. In these conditions, the risk of hypothermia is very high, and prolonged exposure to the water can be hazardous to your health. If you decide to swim, it is important to have the appropriate gear, such as a wetsuit. Typically, only experienced swimmers or those who practice winter swimming venture into such waters. 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 |
|---|---|---|---|
| APR 11 | 5.2°C | 11.0°C | |
| APR 12 | 4.9°C | 11.0°C | |
| APR 13 | 4.5°C | 11.0°C | |
| APR 14 | 5.8°C | 11.0°C | |
| APR 15 | 4.9°C | 11.0°C | |
| APR 16 | 4.4°C | 11.0°C | |
| APR 17 | 4.5°C | 11.0°C | |
| APR 18 | 4.6°C | 11.0°C | |
| APR 19 | 11.0°C | 4.9°C | |
| APR 20 | 11.0°C | 5.2°C | |
| APR 21 | 11.0°C | 5.6°C | |
| APR 22 | 11.0°C | 5.9°C | |
| APR 23 | 11.0°C | 6.2°C | |
| APR 24 | 11.0°C | 6.5°C | |
| APR 25 | 11.0°C | 6.8°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 | 6°C | 12°C |
| February | 0°C | 8°C | 15°C |
| March | 0°C | 9°C | 17°C |
| April | 2°C | 11°C | 20°C |
| May | 8°C | 15°C | 21°C |
| June | 16°C | 19°C | 22°C |
| July | 17°C | 21°C | 24°C |
| August | 20°C | 24°C | 28°C |
| September | 17°C | 20°C | 22°C |
| October | 5°C | 12°C | 18°C |
| November | 3°C | 7°C | 10°C |
| December | 1°C | 6°C | 11°C |
Roy Lake: Water Temperature by Location
Roy Lake: Weather Forecast
April 19
April 20
April 21
April 22
April 23
Location & Local Information
Roy Lake in northeastern South Dakota experiences typical continental seasonal variation in water temperature. In spring the surface water often sits between about 40–60°F (4–16°C) as runoff and cool air temperatures keep the lake chilly. By summer the top layer commonly warms to roughly 70–80°F (21–27°C), and during warm spells can approach the mid-80s°F (around 29°C). Early fall sees a cooling trend back toward 60–70°F (16–21°C), while winter brings ice cover and temperatures near freezing, about 32°F (0°C). Deeper parts of the lake stay noticeably colder than the surface throughout the year, sometimes by 10–15°F (6–8°C), so temperature stratification is a consideration for swimmers and boaters.
Swimming at Roy Lake is allowed, generally during the warmer months when surface temperatures are comfortable. Designated beach areas in the state park are intended for recreational swimming, but conditions vary with weather, water quality, and park staffing; beaches may be unguarded and water quality advisories or seasonal closures can occur. Cold shock from spring or autumn waters and the hazards of ice in winter make swimming unsafe outside the warm season, so visitors should heed posted signs, assess conditions before entering, and follow basic water safety practices.