Sidney Weather in September

What's the weather like in Sidney (Montana) in September 2025?

The climate in Sidney during September can be summarized as mild and reasonably dry.

September is in the fall / autumn in Sidney and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 22°C (72°F), whilst at night 6°C (42°F) is normal.

Sidney weather averages (imperial / metric)
Daytime temperature 22.1°C 71.7°F
Nightly temperature 5.8°C 42.4°F
Average temperature 13.9°C 57°F
Daily sunshine 9 hrs
Avg rainfall 36 mm 1.4 ins
Rainy days 7 days
Sea temperature 13.9°C 57.1°F
Humidity 59%
Windspeed 17.3kph 11 mph

On average September is the 5th wettest month of the year in Sidney with around 36mm 1.4 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 7 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 Sidney

Sidney average temperature in September

September rainfall

Sidney average rain in September

September hourly sunshine

Sidney 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 Sidney 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

Sidney weather stats

Sidney weather statistics
Hottest month: July 29.7°C 85.5°F
Driest month: February 8mm 0.3ins
Sunniest month: July 12.7hrs
Coldest month: January -6.2°C 20.8°F
Wettest month: June 76mm 3ins
Map showing location of Sidney (47.71668, -104.15633) Sidney map pin © Google

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