Coffeen Lake — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Coffeen Lake, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Coffeen Lake today is 18.8°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 |
|---|---|---|---|
| OCT 5 | 20.8°C | 21.0°C | |
| OCT 6 | 20.2°C | 21.0°C | |
| OCT 7 | 19.9°C | 21.0°C | |
| OCT 8 | 18.9°C | 21.0°C | |
| OCT 9 | 19.8°C | 21.0°C | |
| OCT 10 | 20.1°C | 21.0°C | |
| OCT 11 | 19.3°C | 21.0°C | |
| OCT 12 | 19.6°C | 21.0°C | |
| OCT 13 | 21.0°C | 18.9°C | |
| OCT 14 | 21.0°C | 19.0°C | |
| OCT 15 | 21.0°C | 19.1°C | |
| OCT 16 | 21.0°C | 19.2°C | |
| OCT 17 | 21.0°C | 19.4°C | |
| OCT 18 | 21.0°C | 19.5°C | |
| OCT 19 | 21.0°C | 19.6°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 | 0°C | 2°C | 4°C |
| February | 1°C | 5°C | 9°C |
| March | 3°C | 9°C | 14°C |
| April | 6°C | 13°C | 20°C |
| May | 15°C | 20°C | 24°C |
| June | 20°C | 25°C | 29°C |
| July | 24°C | 30°C | 35°C |
| August | 23°C | 28°C | 32°C |
| September | 22°C | 27°C | 32°C |
| October | 15°C | 21°C | 27°C |
| November | 7°C | 13°C | 18°C |
| December | 3°C | 8°C | 12°C |
Coffeen Lake: Water Temperature by Location
Coffeen Lake: Weather Forecast
October 13
October 14
October 15
October 16
October 17
October 18
Location & Local Information
Coffeen Lake is a man-made cooling reservoir in central Illinois whose temperatures reflect seasonal changes and the influence of power-plant discharges. In winter the surface commonly drops to roughly 34–45°F (1–7°C). During spring warming the lake often ranges from about 45–65°F (7–18°C) as runoff and air temperatures moderate. Summer surface temperatures typically sit between roughly 70–90°F (21–32°C), though areas near plant outfalls can be noticeably warmer; deeper water remains cooler than the sun-warmed surface. In autumn the lake cools back toward roughly 50–70°F (10–21°C). Localized variation by depth, time of day and proximity to discharge channels is common, so measured temperatures can differ markedly from these general bands.
Swimming at Coffeen Lake is generally restricted rather than encouraged because the reservoir is used for industrial cooling and presents safety and regulatory concerns. Warm-water outflows can create sudden temperature gradients and strong currents, submerged structures and intake equipment pose hazards, and boating and fishing activity increase collision risk. For these reasons authorities and the operating company typically limit or prohibit casual swimming; visitors are advised to follow posted rules and to use the lake for permitted activities such as boating or fishing where allowed.