St. Charles Weather in September

In St. Charles, September brings high daytime temperatures around 27°C (81°F), with nights cooling to 15°C (59°F). Expect quite a bit of rainfall this month.

Rainfall in St. Charles in September

Historically, the month has about 8 days of rain, averaging 96 mm (3.8 in) in total. Individual showers can be quite heavy this month. A proper umbrella or rain jacket is worth having.

Temperature in St. Charles in September

If you're visiting St. Charles in September, expect perfect temperatures with highs of 27°C (81°F) and overnight lows of 15°C (59°F). Conditions stay fairly consistent through the month, making it easier to plan what to wear. At 15°C (59°F) overnight, it can feel quite a bit cooler after dark. Worth packing something warmer for evenings, but the cooler temperatures are ideal for sleeping.

Sunshine in St. Charles in September

There are approximately 235 hours of sunshine this month, resulting in mostly clear days.

So this is a great month to visit if you prefer dry days with pleasant temperatures.

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• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our St. Charles's climate page.

St. Charles Temperature in September

Min Temperature 15°C (59°F)  

Max Temperature 27°C (81°F)  

Chance of Rain 28%  

Precipitation 96 mm (3.8 in)  

Rainy days 8 days  

Humidity 71% *  

Sunshine 235 hours *  

Percentage Sunshine 63% *  

* Data from: St. Louis, the United States of America (30 KM, 18 Miles).

What to Wear in St. Charles in September

Warm temperatures in September make for comfortable sightseeing weather. Pack breathable fabrics like cotton shirts, knee-length shorts or skirts, and comfortable walking shoes. A thin long sleeve for indoor spaces is handy. Prepare for significant rainfall with proper waterproof clothing and shoes. You'll definitely want to pack sunglasses and sunscreen. There will be plenty of bright sunshine this month.

What To Do in St. Charles in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

9/10

Cycling

7/10

Walking

7/10

Camping

8/10

Outdoor sports

7/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit the United States of America, check out our St. Charles's climate page.

More climate data for St. Charles

Temperature Rainfall Sunshine Humidity

See the full St. Charles climate overview or explore weather in the United States of America.