Weather in Trieste in September 2025
Average weather
Average temperature in Trieste in September
Going from a maximum of +30°C during the day to a minimum of +17°C during the night, the temperature in September averages around +27°C.
The average maximum temperature goes up 0% by the end of the month, compared with the beginning of the month, from +27°C to +27°C.
Is Trieste warm or cold in September?
Trieste is typically warm in September.
Maximum temperatures go down compared to the previous month from +29°C to +24°C. The minimum temperature also goes down from +20°C to +16°C.
It’s generally warm, but pack a long-sleeve shirt for evenings.
Take a look at how September is compared to other months in Trieste:
Water temperature in Trieste in September
Water in Trieste in September is Comfortable. It varies from +20°C to +26°C, with an average of +23°C. This is almost similar to the air temperature, which averages +24°C.
The water temperature in September is one of the warmest of the entire year:
Can you swim in Trieste in September?
Climate in Trieste in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +29°C | +24°C | +19°C | ||||
| Min. temperature | ||||||
| +8°C | +6°C | -1°C | ||||
| Max. temperature | ||||||
| +37°C | +32°C | +30°C | ||||
| Rainfall | ||||||
| 101 mm | 152 mm | 156 mm | ||||
| Wind | ||||||
| 1 m/s | 1 m/s | 2 m/s | ||||
| Avg. water temperature | ||||||
| +25°C | +23°C | +19°C | ||||
| Humidity | ||||||
| 64% | 67% | 70% | ||||
| Air pressure | ||||||
| 1013 HPa | 1015 HPa | 1017 HPa | ||||
| Sunny days | ||||||
| 14 | 11 | 10 | ||||
| Cloudy days | ||||||
| 4 | 5 | 6 | ||||
| Rainy days | ||||||
| 9 | 10 | 13 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September weather is still as good as in August. It’s getting colder in September. From +29°C in the day, the average maximum temperature lowers to +24°C. Prepare for more rain. Average rainfall goes from 101 mm to 152 mm. Humidity rises from 64% to 67%. The average wind speed doesn’t change much during September, staying around 1 m/s. The days becoming less sunny, going from 14 sunny days in August to 11 in September.
October brings much the same weather, it remains good.
Wind
The average wind speed is 2 m/s getting up to 5 m/s which is a light breeze; barely moving the tree leaves.
The average wind speed in Trieste is gradually increasing during September, going from 1 m/s to 2 m/s over the course of the month.
Rain
How was the weather last September in Trieste?
Climate Change over Years
The climate in Trieste in September has not changed much over the last 43 years.
The average temperature was the lowest in 1980 (+17°C) and the highest in 2022 (+20°C). The driest year was 2003 with only 712 mm of rainfall, and the wettest year was 2019 with 2509 mm.
FAQ
Is September a good time to visit Trieste?
Can you sunbathe in Trieste in September?
Can you swim in Trieste in September?
Is Trieste rainy in September?
Is it sunny in Trieste in September?
Other cities in Italy
Monthly weather in Trieste
Source of the data
For this page, we’ve looked at the typical weather in Trieste, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.