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Illinois River

Illinois River Current Water Temperature and Forecast

On this page, you will find comprehensive information about the water temperature in Illinois River, including current readings, historical data and trends, monthly averages, as well as weather forecasts and upcoming temperature predictions. We find every spot where you can swim and tell you what the water temperature is there today and throughout the year.

Current Water Temperature in Illinois River

12.4°C

TODAY

11.7°C

YESTERDAY

8.8°C

A WEEK AGO

As of today, the minimum water temperature in the Illinois River ranges from 50°F (10°C) to 54°F (12°C). The water is slightly warmer, but still cool for most people. Swimming in such conditions is possible, but for most people, the time spent in the water should be limited to avoid hypothermia. Even experienced swimmers may feel discomfort if they stay in the water for too long. To improve comfort and safety, a wetsuit can be used.

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.

Analysis, Historical Data, and Forecast of Water Temperature

Water Temperature Chart for Illinois River Over the Last 30 Days

Today the water temperature in Illinois River is higher than the same day in previous years. The water temperature range here in April is from 5°C to 16°C. The water temperature is trending upward, and it has increased both over the past 30 days and the past week.

The forecasted water temperature values for Illinois River are presented in the table below.

The actual water temperature values near the shore may differ by a few degrees from the stated values. For the development of the forecast, we use our own mathematical model that takes into account the current water temperature changes, historical data, and key weather trends, including wind strength and direction, and air temperature in each specific region.

Daily Water Temperature Chart

DateCurrentAverageForecast
Apr 138.8°C9.9°C
Apr 149.5°C9.9°C
Apr 158.9°C9.9°C
Apr 168.7°C9.9°C
Apr 178.8°C9.9°C
Apr 189.1°C9.9°C
Apr 1911.7°C9.9°C
Apr 2012.4°C9.9°C
Apr 219.9°C12.2°C
Apr 229.9°C12.1°C
Apr 239.9°C12.0°C
Apr 249.9°C11.9°C
Apr 259.9°C11.8°C
Apr 269.9°C11.7°C
Apr 279.9°C11.6°C
Apr 289.9°C11.5°C
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast

Water Temperature Ranges in Illinois River by Month

January

MinimumAverageMaximum
3°C4.2°C9°C

February

MinimumAverageMaximum
3°C5.3°C9°C

March

MinimumAverageMaximum
3°C6.7°C11°C

April

MinimumAverageMaximum
5°C9.9°C16°C

May

MinimumAverageMaximum
8°C13.4°C21°C

June

MinimumAverageMaximum
14°C18.5°C22°C

July

MinimumAverageMaximum
17°C20°C24°C

August

MinimumAverageMaximum
17°C21.4°C23°C

September

MinimumAverageMaximum
11°C17.6°C19°C

October

MinimumAverageMaximum
8°C13.3°C16°C

November

MinimumAverageMaximum
3°C8.1°C16°C

December

MinimumAverageMaximum
3°C4.7°C8°C

Monthly Water Temperature Histogram for Illinois River

Water Temperature in Cities and Towns on Illinois River

Ottawa
United States (Illinois)
11.4°C
Morris
United States (Illinois)
12.5°C
United States (Illinois)
11.6°C

Illinois River Weather

APRIL 20

8°C / 15°C
slight rain

rain: 66% | wind: 31 km/h

APRIL 21

7°C / 17°C
moderate rain showers

rain: 68% | wind: 39 km/h

APRIL 22

7°C / 25°C
partly cloudy

rain: 13% | wind: 26 km/h

APRIL 23

13°C / 21°C
slight rain

rain: 19% | wind: 23 km/h

Water Temperature in Illinois River: General Trends and Swimming Opportunities

Source Confluence of the Kankakee and Des Plaines Rivers
• location Grundy County, Illinois, United States
Mouth Mississippi River
• location Grafton, Illinois, United States
• elevation 417 ft (127 m)
Length 273 mi (439 km)

The Illinois River, flowing through the heart of Illinois, is a major waterway with diverse recreational opportunities. Its water temperature varies with the seasons, typically ranging from 35°F to 50°F (2°C to 10°C) during the cooler months and warming to 65°F–75°F (18°C–24°C) in the summer. These warmer temperatures in the summer make parts of the river more inviting for water-based activities, though swimming is not the primary focus for most visitors.

Swimming in the Illinois River is possible but is generally limited to specific areas where conditions are safe. Factors like water quality, variable currents, and boat traffic can make swimming less practical in many sections. Designated spots or nearby recreational areas, particularly in tributaries or smaller, calmer sections of the river, are better suited for a refreshing dip. The river is widely enjoyed for boating, fishing, and wildlife observation, providing locals and visitors with numerous ways to experience its beauty and significance in the region.

Geographical Location of Illinois River

Nearby Rivers

Frequently Asked Questions About Illinois River and its Water Temperatures

What is the current water temperature in Illinois River?

The water temperature today in Illinois River ranges from 53°F (11.4°C) to 55°F (12.5°C).

What is the water temperature in Illinois River during the summer months?

The average water temperature in Illinois River during the summer months is typically between 65°F to 71°F (19°C to 21°C), and it can reach up to 75°F (24°C) at its warmest. However, in some years, the temperature may exceed this range.

What is the water temperature in Illinois River in May?

The average water temperature in Illinois River in May ranges from 46°F to 70°F (8°C to 21°C).

What is the water temperature in Illinois River in September?

The average water temperature in Illinois River in September is typically between 52°F to 66°F (11°C to 19°C).

Where does Illinois River flow?

Illinois River flows through United States (Illinois).

Is it possible to swim in the Illinois River?

Yes, it is possible to swim in the Illinois River. However, safety and water quality may vary, so it's advisable to check local conditions.

What major cities are located on Illinois River?

Cities along the course of Illinois River include Peoria (Illinois).