Galissas weather in September 2025

Q: How hot is it in Galissas in September?

Daytime temperatures usually reach 25°C in Galissas in September with low heat and humidity, falling to 19°C at night.

Q: How sunny is it in Galissas in September?

There are normally 10 hours of bright sunshine each day in Galissas in September - that's 84% of daylight hours.

Q: How warm is the sea around Galissas in September?

The average sea temperature around Galissas in September is 23°C.

Q: Does it ever rain in Galissas in September?

There is usually 1 day with some rain in Galissas in September and the average monthly rainfall is 12mm.

Expect 25°C daytime maximum temperatures in the shade with on average 10 hours of sunshine per day in Galissas in September. Check more long-term weather averages for Galissas in September before you book your next holiday to Syros in 2025/2026.

25
25°C max day temperature
10
10 hours of sunshine per day
1
1 day with some rainfall
19
19°C min night temperature
12
12 hours of daylight per day
L
Low heat & humidity
12
12 mm of monthly rainfall
7
7 (High) UV index
23
23°C sea temperature

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The September weather guide for Syros, represented by Galissas, (Galissas) 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)