St John weather in September 2025

Expect 18°C daytime maximum temperatures in the shade with on average 6 hours of sunshine per day in St John in September. Check more long-term weather averages for St John in September before you book your next holiday to New Brunswick in 2025/2026.

  • 18°C maximum daytime temperature in September in St John18
    18°C max day temperature
  • 6 hours of sunshine per day
  • 11 days with some rainfall in September in St John11
    11 days with some rainfall
  • 10°C minimum night-time temperature in September in St John10
    10°C min night temperature
  • 12 hours of daylight per day in September in St John12
    12 hours of daylight per day
  • No heat & humidity in September in St John0
    No heat & humidity
  • 104 mm monthly rainfall in September in St John104
    104 mm of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in St John5
    5 (Moderate) UV index
  • 13°C sea temperature in September in St John13
    13°C sea temperature

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The September weather guide for New Brunswick (St John) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm)  |  Imperial (°F / inches)

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How hot is it in St John in September?

Daytime temperatures usually reach 18°C in St John in September, falling to 10°C at night.

How sunny is it in St John in September?

There are normally 6 hours of bright sunshine each day in St John in September - that's 46% of daylight hours.

How warm is the sea around St John in September?

The average sea temperature around St John in September is 13°C.

Does it rain in St John in September?

There are usually 11 days with some rain in St John in September and the average monthly rainfall is 104mm.

What is the chance of a hurricane in St John in September?

On average less than 1 day in September in St John is likely to be affected by the passage of one or more tropical storms.

St John September sunrise & sunset times

Browse the sunrise and sunset times for St John in September 2025. Select a month to view St John sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:46 19:01
Monday, 15th September 2025 06:03 18:35
Tuesday, 30th September 2025 06:22 18:06

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