Illinois Beach State Park water temp
This data the coastal Illinois Beach State Park water temperature today, tomorrow and the upcoming days. Besides, you can also get information about the weather and surf forecast, as well as the data on sunrise / sunset and moonrise / moonset at a given point on any given day.
Current water temperature in Illinois Beach State Park
Water temperature in Illinois Beach State Park today is 68.5°F. Based on our historical data over a period of ten years, the warmest water in this day in Illinois Beach State Park was recorded in 2024 and was 71.1°F, and the coldest was recorded in 2019 at 64.4°F. Water temperature in Illinois Beach State Park is expected to drop to 66.4°F in the next 10 days. September average water temperature in Illinois Beach State Park is 68°F, the minimum temperature is 59.7°F, and the maximum is 74.1°F.
The swimming season in Illinois Beach State Park lasts from July to September. During those months, Illinois Beach State Park water temperature does not drop below 68°F and therefore suitable for comfortable swimming. The average water temperature in Illinois Beach State Park in winter reaches 37.4°F, in spring 40.6°F, in summer the average temperature rises to 66.7°F, and in autumn it is 58.1°F.
Illinois Beach State Park water temperature now
| September 13, 2025 |
|---|
| today temp |
| 68.5°F |
| September 12, 2025 |
|---|
| yesterday temp |
| 68.2°F |
Surf Forecast in Illinois Beach State Park for today
Another important indicators for a comfortable holiday on the beach are the presence and height of the waves, as well as the speed and direction of the wind. Please find below data on the swell size for Illinois Beach State Park. We calculate the swell size based on the mean wave height (trough to crest) of each third highest wave. For more information on surf forecasts for the next ten days, please visit sea state forecast Illinois Beach State Park. Data in table shown for September 13, 2025, time in GMT 0 format (you can change the time zone on the sea state forecast page)
| 0-3 h | 3-6 h | 6-9 h | 9-12 h |
|---|---|---|---|
| 0' 10" | 1' 1" | 1' 2" | 1' 0" |
| 0.26 m | 0.32 m | 0.35 m | 0.3 m |
| 12-15 h | 15-18 h | 18-21 h | 21-24 h |
|---|---|---|---|
| 0' 10" | 1' 1" | 1' 5" | 1' 4" |
| 0.25 m | 0.34 m | 0.44 m | 0.41 m |
Surf report in Illinois Beach State Park
Illinois Beach State Park weather forecast
Current temperature and weather
Data in a table show Illinois Beach State Park temperature today (September 13, 2025). For more information and forecast for a few days, go to the weather forecast Illinois Beach State Park.
| 0-3 h | 3-6 h | 6-9 h | 9-12 h |
|---|---|---|---|
 |  |  |  |
| 67.6°F | 67.6°F | 67.3°F | 71.2°F |
| 12-15 h | 15-18 h | 18-21 h | 21-24 h |
|---|---|---|---|
 | | | |
| 77.2°F | 78.3°F | 77°F | 73.8°F |
You may also be interested in other sections of our site for Illinois Beach State Park: Sunrise and Sunset, Tides
Illinois Beach State Park water temperature by month
These figures shows the average, minimum and maximum monthly water temperature in Illinois Beach State Park. In addition to the table values, the graph below displays of changes average surface temperature during the year. Values are calculated based on the data over the past 10 years. Using them, you can check the water temperature in Illinois Beach State Park on any day of this period that interests you. Click on the month link and you will see a table for each day, or alternatively you can view the temperature curve of the month and select 2 different years you want to compare, either in a table or as a curve
Chart monthly average water temperature in Illinois Beach State Park
