The temperatures in Opatija in September are comfortable with low of 13°C and and high up to 21°C.
You can expect rain for roughly half of the month of September in Opatija. 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 Opatija in September 2025.
If you’re planning to visit Opatija in the near future, we highly recommend that you review the 14 day weather forecast for Opatija before you arrive.