Grass Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Grass Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Grass Lake today is 27.5°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature ranges from 79°F (26°C) to 82°F (28°C). This is very warm water, allowing for extended stays without any discomfort. Swimming in these conditions will be particularly enjoyable, making it the ideal temperature range for those who want to relax in the sea. Additionally, water in this temperature range is suitable for children and elderly people, as it is comfortable for prolonged stays. 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 |
|---|---|---|---|
| JUL 14 | 22.9°C | 22.1°C | |
| JUL 15 | 25.1°C | 22.1°C | |
| JUL 16 | 27.3°C | 22.1°C | |
| JUL 17 | 27.4°C | 22.1°C | |
| JUL 18 | 27.4°C | 22.1°C | |
| JUL 19 | 27.4°C | 22.1°C | |
| JUL 20 | 27.5°C | 22.1°C | |
| JUL 21 | 26.9°C | 22.1°C | |
| JUL 22 | 22.1°C | 27.2°C | |
| JUL 23 | 22.1°C | 27.0°C | |
| JUL 24 | 22.1°C | 26.7°C | |
| JUL 25 | 22.1°C | 26.4°C | |
| JUL 26 | 22.1°C | 26.2°C | |
| JUL 27 | 22.1°C | 25.9°C | |
| JUL 28 | 22.1°C | 25.6°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 | 3°C | 12°C | 20°C |
| May | 7°C | 14°C | 21°C |
| June | 14°C | 18°C | 23°C |
| July | 17°C | 22°C | 28°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 | 5°C | 8°C |
Grass Lake: Water Temperature by Location
Grass Lake: Weather Forecast
July 22
July 23
July 24
July 25
July 26
Location & Local Information
Grass Lake in eastern South Dakota follows the region’s seasonal pattern for surface water temperatures. In spring the lake typically runs cool as it thaws, roughly 40–60 °F (4–16 °C). By early summer surface temperatures often rise into the mid‑60s to upper‑70s °F (18–26 °C) on warm, calm days, with the warmest readings usually occurring in July and August. During autumn the water cools again, generally falling to the 50–65 °F range (10–18 °C) as air temperatures drop. In winter the lake freezes or hangs near 32 °F (0 °C) at the surface when ice is present; under‑ice temperatures remain close to 32 °F (0 °C) until spring thaw.
Swimming at Grass Lake is possible during the ice‑free months and is commonly done when water temperatures are comfortably warm, though actual access and permitted uses depend on local management and any posted advisories. Water quality, including occasional algae (blue‑green algae) blooms, can limit or discourage swimming for health reasons, and cooler waters below about 70 °F (21 °C) may feel uncomfortable without a wetsuit. Always check local signs or contacts for current water‑quality advisories, access rules, and safety information before entering the water, and avoid swimming when ice is present.