The highest day temperature in September 2025 was 85°F. The lowest night temperature was 53°F. The average values for day and night temperatures during September were 76.9°F и 61.7°F respectivly.

The average sea surface temperature in September 2025 for Piran was 78.2°F. The maximum and minimum values were 75.6°F and 80.2°F respectively.

Most of the days in September are sunny but you can also expect cloudy and gloomy days.

Precipitation total in September for Piran is 4.1 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 5.6 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Piran in September is 8.8 hours.