Lake Mattoon — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Mattoon, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Mattoon today is 28.2°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
✅ As of today, the minimum water temperature is above 82°F (28°C). This is very warm water, which may feel almost hot to most people. Swimming in such conditions is perfect for those seeking relaxation and comfort in the water. These waters are often preferred for relaxation in hot weather, as the water temperature does not cool the body significantly. However, it is important to remember that in such warm waters, caution is necessary, as prolonged exposure without rest can lead to overheating. 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 |
|---|---|---|---|
| AUG 4 | 27.2°C | 27.0°C | |
| AUG 5 | 27.3°C | 27.0°C | |
| AUG 6 | 27.7°C | 27.0°C | |
| AUG 7 | 28.0°C | 27.0°C | |
| AUG 8 | 28.0°C | 27.0°C | |
| AUG 9 | 28.3°C | 27.0°C | |
| AUG 10 | 28.3°C | 27.0°C | |
| AUG 11 | 28.5°C | 27.0°C | |
| AUG 12 | 27.0°C | 28.1°C | |
| AUG 13 | 27.0°C | 28.1°C | |
| AUG 14 | 27.0°C | 28.0°C | |
| AUG 15 | 27.0°C | 28.0°C | |
| AUG 16 | 27.0°C | 27.9°C | |
| AUG 17 | 27.0°C | 27.8°C | |
| AUG 18 | 27.0°C | 27.8°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 | 3°C | 6°C |
| February | 1°C | 5°C | 8°C |
| March | 3°C | 9°C | 14°C |
| April | 7°C | 13°C | 19°C |
| May | 16°C | 19°C | 22°C |
| June | 20°C | 24°C | 27°C |
| July | 22°C | 26°C | 30°C |
| August | 24°C | 27°C | 30°C |
| September | 22°C | 26°C | 29°C |
| October | 15°C | 19°C | 23°C |
| November | 7°C | 11°C | 15°C |
| December | 1°C | 5°C | 8°C |
Lake Mattoon: Water Temperature by Location
Lake Mattoon: Weather Forecast
August 12
August 13
August 14
August 15
August 16
Location & Local Information
Lake Mattoon, a reservoir in central Illinois, experiences pronounced seasonal swings in surface water temperature. In summer months the surface commonly warms to roughly 75–85°F (24–29°C), with the warmest spells occasionally pushing mid-80s°F (around 29°C). Spring brings a steady warm-up, typically in the range of about 45–65°F (7–18°C) depending on weather patterns, while fall cools back through roughly 50–70°F (10–21°C). During winter the lake’s surface often approaches freezing, commonly around 32–40°F (0–4°C), and parts of the lake can ice over in sustained cold. Temperatures vary by depth, time of day and recent weather, with shallow nearshore water warming and cooling faster than deeper areas.
Swimming is generally allowed at Lake Mattoon in designated recreational areas during the warmer part of the year because the lake is managed for multiple public uses, including boating and swimming. Local authorities and park managers set rules and open specific beach or swim zones for safety, water-quality monitoring and to keep swimmers separate from boat traffic. Swimmers should observe posted signage and advisories: early- or late-season cold water, hazardous conditions, or occasional algal blooms can make swimming unsafe even when permitted.