The temperatures in Postojna in September are comfortable with low of 10°C and and high up to 21°C.
You can expect rain for roughly half of the month of September in Postojna. We’re expecting roughly 8 to 15 days of rain, so your rubber boots and umbrella are going to see plenty of use this month if you’re keen on staying dry.
Our weather forecast can give you a great sense of what weather to expect in Postojna in September 2025.
If you’re planning to visit Postojna in the near future, we highly recommend that you review the 14 day weather forecast for Postojna before you arrive.
Temperatures
21° / 10°
Rainy Days
9
Snowy Days
0
Dry Days
21
Rainfall
233
mm
Sun Hours
10.5
Hrs
