Opatija Weather in September

Opatija in September averages 22°C (72°F) during the day and 14°C (57°F) at night. September is part of the rainy season, so frequent rainfall is typical.

Rainfall in Opatija in September

Opatija is in the rainy season in September, with rain on around 13 days and an average of 215 mm (8.5 in). Rain during the rainy season here tends to be intense rather than just persistent drizzle. Expect significant downpours.

Temperature in Opatija in September

Daytime temperatures in Opatija reach 22°C (72°F) in September, dropping to 14°C (57°F) at night. The difference between afternoon and evening temperatures is usually noticeable. With lows of 14°C (57°F), nights are cool. If you're out after dark, an extra layer will keep you comfortable. The cooler air at night is also great for getting a good rest.

Sunshine in Opatija in September

There are approximately 202 hours of sunshine this month, despite being the rainy season. Rain often arrives in the late afternoon or evening, keeping mornings and early afternoons sunny. Even during the wet season, it could still be a nice time to visit.

Average water temperature in September

The water temperature is 24°C (75°F), which most people find very comfortable. A good month for swimming and water sports.

Should you favor a climate that's both dry and comfortably warm, May, June, July and August typically offer the most agreeable circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.

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For a detailed overview over the year and the best time to visit Croatia, check out our Opatija's climate page.

Opatija Temperature in September

Min Temperature 14°C (57°F)  

Max Temperature 22°C (72°F)  

Water Temperature 24°C (75°F) *  

Chance of Rain 42%  

Precipitation 215 mm (8.5 in)  

Rainy days 13 days  

Humidity 64% *  

Sunshine 202 hours *  

Percentage Sunshine 57% *  

* Data from: Rijeka, Croatia (7 KM, 4 Miles).

Daily Historical Temperatures

50-year average (1976-2025)

Based on our historical records, temperatures in Opatija typically drop from around 25°C (77°F) at the start of September to approximately 22°C (72°F) by the end. Nights are pleasant, with lows typically ranging from 13°C (55°F) to 17°C (63°F).

Average temperatures in September

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Daily Historical Precipitation

50-year average (1976-2025)

Average daily rainfall for each day of the month based on long-term records.

Average precipitation in September

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Historical weather for Opatija in September

Browse day-by-day weather records for Opatija spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.

Historical weather Temperatures Precipitation

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Opatija historical weather extremes in September

Based on weather observations in Opatija between 1976 and 2025, these are the recorded extremes during September.

• On September 1, 2024, temperatures climbed to 33°C (91°F), marking the warmest September day on record.
• The lowest daytime temperature in September was 11°C (52°F), recorded on September 18, 1977.
• The lowest overnight temperature recorded in September was 4°C (39°F) (September 7, 1992).

What to Wear in Opatija in September

For Opatija in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. Also bring a poncho, it will rain a lot! Waterproof everything you can. Expect water temperatures of around 24°C (75°F), which is ideal for taking a refreshing dip. Bring swimwear and consider packing a towel for drying off. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.

What To Do in Opatija in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

7/10

Camping

6/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Croatia, check out our Opatija's climate page.

More climate data for Opatija

Temperature Rainfall Sunshine Humidity Water Temp

See the full Opatija climate overview or explore weather in Croatia.