September is a warm and rainy time for sunbathing in Illinois. September is an excellent month for swimming in Illinois with very warm sea temperatures. Consider visiting Illinois in the months of June, July, August, September, for the best beach weather. Also consider one of our other suggestions for September.
The average maximum temperature in Illinois in September is 24°. The average maximum temperature is 28° in the previous month and 17° in the next month.
The average temperature in Illinois in September is 20°. The average temperature ranges is 23° in the previous month and 13° in the next month.
The average minimum temperature in Illinois in September is 15°. The minimum temperature is 19° in the previous month and 8° in the next month.
The average day light hours per day in Illinois in September are 12.5 and there are 8.5 hours of sunshine per day on average during September making it a sunny month with few clouds.
The ultraviolet index in Illinois in September is typically 6.5 during September. An ultraviolet index reading of 6 to 7 indicates a high risk of harm from unprotected sun exposure. Unprotected skin risks burning in less than 20 minutes. Protection against skin and eye damage is needed. Tanning will be safest before 10am and after 4pm. For those with sensitive skin stay in the shade and wear protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 30+ sunscreen every 2 hours, even on cloudy days. Watch out for relections from water that may increase ultraviolet exposure.
The average sea water temperature in Illinois in September is 27° which is very warm and ideal for relaxing and swimming for the whole day.
The average total rainfall in Illinois in September is 66cm and on average there are 10.2 rainy days in September making it a wet time to visit the beach.
The maximum dew point (an indicator of humidity) in Illinois in September is 15° which is comfortable for everyone. The dew point is 19° in the previous month and 9° in the next month.
The average maximum relative humidity in Illinois in September is typically 84.1%. The maximum relative humidity is 84% in the previous month and 83.4% in the next month.
The average relative humidity in Illinois in September is typically 64.8%. The average relative humidity is 65.2% in the previous month and 65.2% in the next month.
The average maximum wind speed in Illinois in September is typically 25kmh. The average maximum wind speed is 26kmh in the previous month and 28kmh in the next month.
The average wind speed in Illinois in September is typically 13kmh. The average wind speed is 12kmh in the previous month and 15kmh in the next month.
The average wind direction in Illinois in September is from the South-Southwest.
