Lake Sinai — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Sinai, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Sinai today is 21.9°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature ranges from 68°F (20°C) to 74°F (23°C). The water is warm and pleasant for swimming, and in this range, one can stay in the water for extended periods without the risk of hypothermia. This is the ideal temperature for relaxation, swimming, and water sports. Families with children, as well as outdoor enthusiasts, will enjoy swimming and time spent in the water. For most people, this is the optimal temperature for a comfortable beach experience. 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 3 | 19.2°C | 18.5°C | |
| JUN 4 | 19.1°C | 18.5°C | |
| JUN 5 | 20.3°C | 18.5°C | |
| JUN 6 | 20.7°C | 18.5°C | |
| JUN 7 | 21.6°C | 18.5°C | |
| JUN 8 | 21.6°C | 18.5°C | |
| JUN 11 | 18.5°C | 21.7°C | |
| JUN 12 | 18.5°C | 21.6°C | |
| JUN 13 | 18.5°C | 21.4°C | |
| JUN 14 | 18.5°C | 21.2°C | |
| JUN 15 | 18.5°C | 21.1°C | |
| JUN 16 | 18.5°C | 20.9°C | |
| JUN 17 | 18.5°C | 20.7°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 | 0°C | 6°C | 12°C |
| February | 0°C | 8°C | 15°C |
| March | 1°C | 9°C | 17°C |
| April | 3°C | 12°C | 20°C |
| May | 7°C | 15°C | 23°C |
| June | 15°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 | 19°C |
| November | 3°C | 7°C | 10°C |
| December | 0°C | 5°C | 8°C |
Lake Sinai: Water Temperature by Location
Lake Sinai: Weather Forecast
June 9
June 10
June 11
June 12
June 13
Location & Local Information
Lake Sinai, like many small prairie lakes in South Dakota, experiences pronounced seasonal swings in surface water temperature. In spring the surface typically warms from roughly 40–60°F (4–15°C) as thaw and runoff progress. Summer surface temperatures commonly reach about 68–80°F (20–27°C) on warm days, and can briefly exceed that during heat waves. In autumn the water cools back to around 45–65°F (7–18°C) before winter settles in; during winter the lake surface often approaches the freezing point, about 32°F (0°C), and will form ice layers so open water temperatures are at or just above freezing beneath the ice.
Swimming at Lake Sinai is generally an activity pursued during the warmer months where public access and beaches exist, but specific permissions depend on local management and posted rules. Recreational swimming is often allowed because the lake is used for boating and fishing as well, yet there may be no lifeguards, and water quality can vary seasonally with algal blooms, runoff after rains, or low clarity that affect safety. For those considering a swim, confirm current advisories, obey signage, and be mindful of cold-water risks early and late in the season, since temperatures below about 70°F (21°C) can feel uncomfortable and increase hypothermia risk with prolonged exposure.