Waterloo Weather in September

The climate in Waterloo during September can be summarized as mild and a little damp.

September is in the fall / autumn in Waterloo and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 22°C (72°F), whilst at night 11°C (52°F) is normal.

On average September is the 2nd wettest month of the year in Waterloo with around 80mm 3.2 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 11 days, although this may vary considerably.

On the flip side this corresponds to an average of 7.3 hours of sunshine per day.

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 Waterloo in September 2025.