Typical Weather in Mount Vernon, IL in September
79° F Avg High
56° F Avg Low
5 Rainy Days
☀️ Temperature Summary
September is a popular time to visit, with an inviting climate featuring warm temperatures. Highs in September are typically around 79°F, which is warmer than usual in Mount Vernon. You can expect overnight lows near 56°F most days. Temperatures will usually fall as the month goes on, with daily high temperatures ranging between 82°F and 73°F.
September is a great time to visit Mount Vernon, with mild temperatures and sunny days being very common.
High Temps Throughout the Year
🎒 What to Pack
Pick up a few of these items to keep your trip fun and comfortable.
☔ Rain Summary
You can expect about a 16% chance of rain for any given day in September. It's one of the drier months of the year for Mount Vernon, with total rainfall for the month around 3 inches.
Rainfall Throughout the Year
Planning a trip to Mount Vernon? Try our free trip weather planner