The highest day temperature in September 2025 was 90°F. The lowest night temperature was 53°F. The average values for day and night temperatures during September were 76.4°F и 64.3°F respectivly.

The average sea surface temperature in September 2025 for Evanston was 71.7°F. The maximum and minimum values were 68.2°F and 74.4°F respectively.

Most of the days in September are sunny but you can also expect cloudy and gloomy days.

Precipitation total in September for Evanston is 0.7 in. It makes september one of the least rainy months of the year.

The average wind speed in September is 8.3 mph. It makes September one of the most windless months of the year for Evanston.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Evanston in September is 8.6 hours.