Monmouth weather in September 2026

Expect daytime maximum temperatures of 18°C in Monmouth, Wales in September based on long-term weather averages. There are 4 hours of sunshine per day on average with 14 days with some rainfall and typically 78 mm of rainfall in the month.

  • 18°C maximum daytime temperature in September in Monmouth18
    18°C max day temperature
  • 4 hours of sunshine per day
  • 14 days with some rainfall in September in Monmouth14
    14 days with some rainfall
  • 9°C minimum night-time temperature in September in Monmouth9
    9°C min night temperature
  • 13 hours of daylight per day in September in Monmouth13
    13 hours of daylight per day
  • No heat & humidity in September in Monmouth0
    No heat & humidity
  • 78 mm monthly rainfall in September in Monmouth78
    78 mm of monthly rainfall
  • UV (maximum) index 4 (Moderate) in September in Monmouth4
    4 (Moderate) UV index

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The September weather guide for Wales (Monmouth) 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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More about Wales

How hot is it in Monmouth in September?

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

How sunny is it in Monmouth in September?

There are normally 5 hours of bright sunshine each day in Monmouth in September - that's 37% of daylight hours.

How warm is the sea around Monmouth in September?

The average sea temperature around Monmouth in September is 17°C.

Does it rain in Monmouth in September?

There are usually 15 days with some rain in Monmouth in September and the average monthly rainfall is 91mm.

Monmouth September sunrise & sunset times

Browse the sunrise and sunset times for Monmouth in September 2026. Select a month to view Monmouth sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Tuesday, 1st September 2026 05:23 18:58
Tuesday, 15th September 2026 05:45 18:26
Wednesday, 30th September 2026 06:10 17:51

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