Saint John Weather in September

The climate in Saint John during September can be summarized as warm and reasonably dry.

September is in the fall / autumn in Saint John and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a comfortable 28°C (82°F), whilst at night 14°C (56°F) is normal.

On average September is the 5th wettest month of the year in Saint John with around 67mm 2.6 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 9.3 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 Saint John in September 2025.