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 19.4°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 2 | 15.9°C | 18.4°C | |
| JUN 3 | 17.9°C | 18.4°C | |
| JUN 4 | 17.8°C | 18.4°C | |
| JUN 5 | 18.6°C | 18.4°C | |
| JUN 6 | 18.9°C | 18.4°C | |
| JUN 7 | 19.1°C | 18.4°C | |
| JUN 8 | 19.3°C | 18.4°C | |
| JUN 10 | 18.4°C | 19.4°C | |
| JUN 11 | 18.4°C | 19.3°C | |
| JUN 12 | 18.4°C | 19.3°C | |
| JUN 13 | 18.4°C | 19.2°C | |
| JUN 14 | 18.4°C | 19.2°C | |
| JUN 15 | 18.4°C | 19.1°C | |
| JUN 16 | 18.4°C | 19.1°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 | 7°C | 14°C | 21°C |
| June | 14°C | 18°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
June 9
June 10
June 11
June 12
June 13
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.