Trieste weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Excellent
Best time to visit: May – September
What is the weather like in Trieste in September?
In September, Trieste is warm: daytime highs average 22 °C, and nights cool down to about 16 °C. The sea averages 22.9 °C – refreshing for a swim. The sun shines for around 7 hours a day. Rain is frequent, with about 10 rainy days and 152 mm in total. All in all, September is an excellent month for a holiday in Trieste.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 90 | 81 | 69 |
| Day | 27° | 22° | 18° |
| Night | 20° | 16° | 12° |
| Sea | 26° | 23° | 19° |
| Sun | 9 h | 7 h | 6 h |
| Rain days | 9 | 10 | 12 |
More details for September
- Daylight
- 12 h 37 min06:42 – 19:19
- UV index
- 5 · moderateclear sky, noon (estimate)All months
- Muggy days
- 4 daysdew point 18 °C or moreAll months
- Wind
- 15 km/haverage daily peakAll months
- Cloud cover
- 48 %on averageAll months
- Hot days
- 0 days30 °C or moreAll months
- Snow days
- 0 days1 cm or more of fresh snow
- Time zone
- UTC+2Europe/Rome
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %68 %
- Few rainy daysweight 30 %57 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in September
- Swimwear
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
Trieste in September: quick answers
Is Trieste hot in September?
Warm rather than hot: in September, daytime highs in Trieste average 22 °C and nights cool to about 16 °C.
Can you swim in Trieste in September?
Yes. In September the sea averages 22.9 °C – refreshing for a swim.
Does it rain much in Trieste in September?
Rain is frequent, with about 10 rainy days and 152 mm in total.
Trieste month by month
The whole year in TriesteAll destinations: ItalyWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences