Lake Henry — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Henry, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Henry today is 19.3°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 | 19.5°C | 18.2°C | |
| JUN 24 | 19.6°C | 18.2°C | |
| JUN 25 | 19.8°C | 18.2°C | |
| JUN 26 | 19.8°C | 18.2°C | |
| JUN 27 | 20.1°C | 18.2°C | |
| JUN 28 | 19.0°C | 18.2°C | |
| JUN 29 | 18.9°C | 18.2°C | |
| JUN 30 | 18.9°C | 18.2°C | |
| JUL 1 | 20.5°C | 19.4°C | |
| JUL 2 | 20.5°C | 19.4°C | |
| JUL 3 | 20.5°C | 19.5°C | |
| JUL 4 | 20.5°C | 19.5°C | |
| JUL 5 | 20.5°C | 19.6°C | |
| JUL 6 | 20.5°C | 19.7°C | |
| JUL 7 | 20.5°C | 19.7°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 | 1°C | 7°C | 12°C |
| February | 1°C | 8°C | 15°C |
| March | 0°C | 9°C | 17°C |
| April | 2°C | 11°C | 20°C |
| May | 6°C | 14°C | 23°C |
| June | 14°C | 18°C | 23°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 | 19°C |
| November | 3°C | 7°C | 10°C |
| December | 0°C | 5°C | 8°C |
Lake Henry: Water Temperature by Location
Lake Henry: Weather Forecast
July 1
July 2
July 3
July 4
July 5
July 6
Location & Local Information
Lake Henry in South Dakota experiences pronounced seasonal changes in water temperature typical of prairie lakes. In winter the surface commonly freezes, with surface temperatures at or just below 32°F (0°C) while deeper water stays closer to about 39°F (4°C). During spring the lake warms from roughly 40–60°F (4–16°C) as ice melts and runoff continues to cool the water. By midsummer surface temperatures often reach the low 70s to low 80s °F (about 21–28°C) on warm, calm days, though deeper areas remain noticeably cooler. In autumn the surface cools back through the 50s into the 40s °F (10–4°C) before the lake refreezes.
Swimming is generally possible during the open-water season and many people do swim from public access points when conditions are favorable, primarily in summer when surface temperatures are most comfortable. However, swimming is not allowed when the lake is ice-covered, and local restrictions or advisories can temporarily prohibit swimming for safety or public‑health reasons (for example, hazardous ice, harmful algal blooms, or posted closures). Swimmers should be mindful that even in summer sudden drops in temperature with depth can increase hypothermia risk, that most sites lack lifeguards, and that checking local signage and conditions before entering the water is advisable.