Round Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Round Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Round Lake today is 21.6°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 2 | 16.2°C | 22.5°C | |
| JUN 3 | 17.2°C | 22.5°C | |
| JUN 4 | 17.4°C | 22.5°C | |
| JUN 5 | 17.6°C | 22.5°C | |
| JUN 6 | 17.8°C | 22.5°C | |
| JUN 7 | 20.9°C | 22.5°C | |
| JUN 8 | 21.3°C | 22.5°C | |
| JUN 10 | 22.5°C | 21.6°C | |
| JUN 11 | 22.5°C | 21.7°C | |
| JUN 12 | 22.5°C | 21.7°C | |
| JUN 13 | 22.5°C | 21.8°C | |
| JUN 14 | 22.5°C | 21.8°C | |
| JUN 15 | 22.5°C | 21.9°C | |
| JUN 16 | 22.5°C | 21.9°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 | 2°C | 6°C | 8°C |
| February | 2°C | 6°C | 9°C |
| March | 3°C | 6°C | 9°C |
| April | 5°C | 8°C | 11°C |
| May | 5°C | 11°C | 18°C |
| June | 16°C | 23°C | 29°C |
| July | 20°C | 25°C | 29°C |
| August | 24°C | 26°C | 29°C |
| September | 11°C | 18°C | 25°C |
| October | 8°C | 14°C | 19°C |
| November | 3°C | 8°C | 12°C |
| December | 3°C | 6°C | 8°C |
Round Lake: Water Temperature by Location
Round Lake: Weather Forecast
June 9
June 10
June 11
June 12
Location & Local Information
Round Lake in northeastern Illinois is a relatively shallow inland lake, so its surface temperature follows seasonal air temperatures closely. In winter the water typically approaches freezing, often around 32–40°F (0–4°C) under open-water conditions and colder where ice forms. During spring warming, surface temperatures commonly rise into the 40–60°F range (4–16°C) as the lake mixes and stratification begins. Summer is when the lake is warmest; typical surface readings are in the 70s °F, roughly 21–27°C, and on hot spells can climb into the upper 70s or low 80s °F (25–28°C). In autumn the surface cools again, generally moving through the 50–65°F band (10–18°C) before returning to winter conditions.
Swimming opportunities exist in summer months when water temperatures are comfortable and local authorities have not issued advisories. Public access, designated beaches, or parks may permit swimming, sometimes with lifeguards during peak season; outside those areas swimming may be allowed but is usually unguarded. Because the lake is shallow and productive, managers monitor water quality and will close or discourage swimming for issues such as high bacterial counts or harmful algal blooms. Ice and cold-water swimming in winter are hazardous and not recommended without proper safety measures and local guidance. Always check current local advisories before entering the water.