Weather in September
September in
LaSalle,
Illinois brings about the start of fall. As the days begin shortening to an average of 12.5 hours, summer's warmth gradually declines, leading to the cooler days of autumn. Colors begin to shift from the vibrant greens of summer to an array of fall hues. September’s mild temperatures and gently decreasing daylight hours pave the way for the more significant changes approaching in
October.
Temperature
September ushers in a minute temperature change in LaSalle, with average high-temperatures reducing from
August's 82.9°F (28.3°C) to a still warm 77°F (25°C). During September, LaSalle reports a marked contrast from daily peak temperatures, with an average nighttime reading of 52°F (11.1°C).
Daylight
In LaSalle, the average length of the day in September is 12h and 28min.
On the first day of September in LaSalle, sunrise is at 6:23 am and sunset at 7:28 pm. On the last day of the month, sunrise is at 6:52 am and sunset at 6:39 pm CDT.
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