Portoroz weather in September 2025

Expect 75°F daytime maximum temperatures in the shade with on average 7 hours of sunshine per day in Portoroz in September. Check more long-term weather averages for Portoroz in September before you book your next holiday to Slovenia in 2025/2026.

  • 75°F maximum daytime temperature in September in Portoroz75
    75°F max day temperature
  • 7 hours of sunshine per day
  • 11 days with some rainfall in September in Portoroz11
    11 days with some rainfall
  • 57°F minimum night-time temperature in September in Portoroz57
    57°F min night temperature
  • 13 hours of daylight per day in September in Portoroz13
    13 hours of daylight per day
  • No heat & humidity in September in Portoroz0
    No heat & humidity
  • 4.6 inches monthly rainfall in September in Portoroz4.6
    4.6 inches of monthly rainfall
  • UV (maximum) index 5 (Moderate) in September in Portoroz5
    5 (Moderate) UV index
  • 72°F sea temperature in September in Portoroz72
    72°F sea temperature

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The September weather guide for Slovenia (Portoroz) 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)  |  Imperial (°F)

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More about Slovenia

How hot is it in Portoroz in September?

Daytime temperatures usually reach 75°F in Portoroz in September, falling to 57°F at night.

How sunny is it in Portoroz in September?

There are normally 7 hours of bright sunshine each day in Portoroz in September - that's 54% of daylight hours.

How warm is the sea around Portoroz in September?

The average sea temperature around Portoroz in September is 72°F.

Does it rain in Portoroz in September?

There are usually 11 days with some rain in Portoroz in September and the average monthly rainfall is 4.6 inches.

Portoroz September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:27 18:43
Monday, 15th September 2025 05:44 18:17
Tuesday, 30th September 2025 06:03 17:48

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