Watertown Weather in September

What's the weather like in Watertown (South Dakota) in September 2025?

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

September is in the fall / autumn in Watertown and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 22°C (72°F), whilst at night 8°C (47°F) is normal.

Watertown weather averages (imperial / metric)
Daytime temperature 22.1°C 71.8°F
Nightly temperature 8.3°C 46.9°F
Average temperature 15.2°C 59.4°F
Daily sunshine 8.8 hrs
Avg rainfall 51 mm 2 ins
Rainy days 8 days
Sea temperature 16.4°C 61.6°F
Humidity 70%
Windspeed 18.4kph 11 mph

On average September is the 6th wettest month of the year in Watertown with around 51mm 2 inches of rain making it a reasonably dry 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 8.8 hours of sunshine per day.

September temperatures in Watertown

Watertown average temperature in September

September rainfall

Watertown average rain in September

September hourly sunshine

Watertown 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 Watertown 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

Watertown weather stats

Watertown weather statistics
Hottest month: July 29°C 84.2°F
Driest month: December 13mm 0.5ins
Sunniest month: July 12.2hrs
Coldest month: January -6.3°C 20.7°F
Wettest month: June 94mm 3.7ins
Map showing location of Watertown (44.89941, -97.11507) Watertown map pin © Google

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