Stillwater Weather in September

What's the weather like in Stillwater (Oklahoma) in September 2025?

The climate in Stillwater during September can be summarized as hot and damp.

September is in the fall / autumn in Stillwater and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a comfortable 30°C (85°F), whilst at night 17°C (62°F) is normal.

Stillwater weather averages (imperial / metric)
Daytime temperature 29.6°C 85.2°F
Nightly temperature 16.5°C 61.6°F
Average temperature 23°C 73.4°F
Daily sunshine 9 hrs
Avg rainfall 107 mm 4.2 ins
Rainy days 8 days
Sea temperature 21.5°C 70.7°F
Humidity 68%
Windspeed 17.3kph 11 mph

On average September is the 2nd wettest month of the year in Stillwater with around 107mm 4.2 inches of rain making it a damp time to visit. This rainfall is typically spread over 8 days, although this may vary considerably.

On the flip side this corresponds to an average of 9 hours of sunshine per day.

September temperatures in Stillwater

Stillwater average temperature in September

September rainfall

Stillwater average rain in September

September hourly sunshine

Stillwater average rain in September

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Stillwater in September 2025.

Other monthly averages

Best places to visit in September

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Stillwater weather stats

Stillwater weather statistics
Hottest month: July 34.5°C 94.1°F
Driest month: January 30mm 1.2ins
Sunniest month: July 12hrs
Coldest month: January 8°C 46.4°F
Wettest month: May 132mm 5.2ins
Map showing location of Stillwater (36.11561, -97.05837) Stillwater map pin © Google

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