Illinois Beach State Park Sea Water Temperature
A cool beach on the James Bay, warmest around August at about 22°C. Today's reading, 7-day forecast, and monthly averages below.
Illinois Beach State Park water temperature
Invigorating and crisp. Tolerable for active swimming, but chilly for prolonged casual bathing.
7-Day Water Temperature Forecast
Illinois Beach State Park Monthly Water Temperature Averages
Historical monthly climatology. The warmest water in Illinois Beach State Park occurs inJuly, August, September, October — peaking at22°C (71.6°F) in August.
Year-Round Water Temperature Curve (°C / °F)
Hover a bar for detailsFull 12-month data table — min / avg / max & swimming comfort
| Month | Min Water Temp | Average Water Temp | Max Water Temp | Swimming Comfort |
|---|---|---|---|---|
| January | 1.5°C | 3.8°C | 5.9°C | Very Cold (< 16°C) |
| February | 0.1°C | 2.4°C | 4°C | Very Cold (< 16°C) |
| March | 0°C | 2.2°C | 5.2°C | Very Cold (< 16°C) |
| April | 1.8°C | 3.6°C | 6°C | Very Cold (< 16°C) |
| May | 2.8°C | 6.9°C | 16.2°C | Very Cold (< 16°C) |
| June | 5.3°C | 13.6°C | 19.8°C | Very Cold (< 16°C) |
| July | 14.9°C | 20.3°C | 24.5°C | Comfortable (20°C – 24°C) |
| August | 20°C | 22°C | 24.7°C | Comfortable (20°C – 24°C) |
| SeptemberCurrent | 16.3°C | 19.5°C | 22.1°C | Cool / Refreshing (16°C – 20°C) |
| October | 9.7°C | 14.4°C | 19.4°C | Very Cold (< 16°C) |
| November | 5.2°C | 9°C | 13.1°C | Very Cold (< 16°C) |
| December | 2.6°C | 5.5°C | 8.3°C | Very Cold (< 16°C) |
Swimming FAQs for Illinois Beach State Park
Is the sea warm enough to swim in Illinois Beach State Park today?
Typical sea surface temperature in Illinois Beach State Park this time of year is 19.5°C (67.1°F) — classified as Cool / Refreshing (16°C – 20°C). Invigorating and crisp. Tolerable for active swimming, but chilly for prolonged casual bathing. Live readings load automatically.
What are the warmest months for swimming in Illinois Beach State Park?
The highest water temperatures in Illinois Beach State Park typically occur duringJuly, August, September, October, when monthly averages reach peak seasonal levels.
What is the typical water temperature in Illinois Beach State Park in September?
Historically in September, water temperatures in Illinois Beach State Park average around19.5°C (67.1°F), fluctuating between a recorded minimum of 16.3°C and a maximum of 22.1°C.