Trieste weather in September
In September, Trieste sees average daytime highs of 21°C and overnight lows near 15°C, with 170 mm of rain across 11.4 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 3rd-wettest month of the year here.
Highs ease over the month, from about 23°C in the first days to 19°C by the end. The sky is clear or mostly clear about 42% of the time in September, and the air most often feels dry.
Daylight stretches from about 13 h 06 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Trieste's 4th-clearest and 7th-windiest month. For the whole year in context, see Trieste's year-round climate.
- Daytime high
- 21°
- 4th warmest
- Overnight low
- 15°
- 9th coldest
- Rainfall
- 170 mm
- 11.4 wet days
- Daylight
- 12 h 18 min
- 5:50 AM – 6:09 PM
- Cloud cover
- 49%
- 4th clearest
- Wind
- 10 km/h
- 7th windiest
- Solar energy
- 3.89 kWh/m²
- Travel score
- 6.4
- out of 10
- Air quality
- Moderate
- PM2.5 12 µg/m³ · 2019
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in September
Highs ease over the month, from about 23°C in the first days to 19°C by the end.
A typical September day in Trieste reaches about 21°C in the afternoon and slips back to 15°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 17°C and 25°C. Set against its neighbours, September runs about 5°C cooler than August and about 5°C warmer than October.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 24 | 23 | 23 | 23 | 23 | 23 | 23 | 22 | 22 | 22 | 22 | 22 | 22 | 21 | 21 | 21 | 21 | 21 | 21 | 20 | 20 | 20 | 20 | 20 | 20 | 19 | 19 | 19 | 19 | 19 |
| Avg low (°C) | 17 | 17 | 17 | 17 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 15 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 13 | 13 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| 1 | 24 | 17 |
| 2 | 23 | 17 |
| 3 | 23 | 17 |
| 4 | 23 | 17 |
| 5 | 23 | 16 |
| 6 | 23 | 16 |
| 7 | 23 | 16 |
| 8 | 22 | 16 |
| 9 | 22 | 16 |
| 10 | 22 | 16 |
| 11 | 22 | 16 |
| 12 | 22 | 15 |
| 13 | 22 | 15 |
| 14 | 21 | 15 |
| 15 | 21 | 15 |
| 16 | 21 | 15 |
| 17 | 21 | 15 |
| 18 | 21 | 15 |
| 19 | 21 | 15 |
| 20 | 20 | 14 |
| 21 | 20 | 14 |
| 22 | 20 | 14 |
| 23 | 20 | 14 |
| 24 | 20 | 14 |
| 25 | 20 | 14 |
| 26 | 19 | 14 |
| 27 | 19 | 14 |
| 28 | 19 | 14 |
| 29 | 19 | 13 |
| 30 | 19 | 13 |
How September really feels in Trieste
Once humidity and wind are folded in, September averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.
September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Trieste weather by month
How September compares with the rest of the year at a glance. September is the 4th-warmest and 3rd-wettest month here — the current month is highlighted below.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 6° / 2° | 90 | 9.5 | 2.7 | 8.9 | 0.5 |
| Feb | 7° / 2° | 97 | 8.6 | 2.9 | 10.1 | 1.1 |
| Mar | 11° / 5° | 101 | 9.7 | 1.6 | 11.6 | 2.7 |
| Apr | 15° / 8° | 110 | 12.1 | 0.5 | 13.3 | 4.2 |
| May | 19° / 13° | 122 | 13 | 0 | 14.7 | 5.8 |
| Jun | 23° / 17° | 111 | 12.2 | 0 | 15.4 | 6.7 |
| Jul | 26° / 19° | 87 | 10.7 | 0 | 15.1 | 7.0 |
| Aug | 26° / 19° | 111 | 10.3 | 0 | 13.9 | 7.0 |
| Sep | 21° / 15° | 170 | 11.4 | 0 | 12.3 | 6.4 |
| Oct | 16° / 11° | 184 | 13 | 0.1 | 10.7 | 4.8 |
| Nov | 11° / 7° | 195 | 13.2 | 1.1 | 9.3 | 2.5 |
| Dec | 7° / 3° | 129 | 10.1 | 2.1 | 8.6 | 0.9 |
Cloud cover in September
The sky is clear or mostly clear about 42% of the time in September.
Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 39%. Skies tend to cloud over as the month goes on.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 67 | 67 | 67 | 67 | 66 | 66 | 66 | 66 | 65 | 65 | 64 | 63 | 64 | 63 | 62 | 62 | 61 | 59 | 59 | 58 | 58 | 57 | 56 | 56 | 55 | 54 | 54 | 53 | 52 | 51 |
| Cloudier (%) | 33 | 33 | 33 | 33 | 34 | 34 | 34 | 34 | 35 | 35 | 36 | 37 | 36 | 37 | 38 | 38 | 39 | 41 | 41 | 42 | 42 | 43 | 44 | 44 | 45 | 46 | 46 | 47 | 48 | 49 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 67 | 33 |
| 2 | 67 | 33 |
| 3 | 67 | 33 |
| 4 | 67 | 33 |
| 5 | 66 | 34 |
| 6 | 66 | 34 |
| 7 | 66 | 34 |
| 8 | 66 | 34 |
| 9 | 65 | 35 |
| 10 | 65 | 35 |
| 11 | 64 | 36 |
| 12 | 63 | 37 |
| 13 | 64 | 36 |
| 14 | 63 | 37 |
| 15 | 62 | 38 |
| 16 | 62 | 38 |
| 17 | 61 | 39 |
| 18 | 59 | 41 |
| 19 | 59 | 41 |
| 20 | 58 | 42 |
| 21 | 58 | 42 |
| 22 | 57 | 43 |
| 23 | 56 | 44 |
| 24 | 56 | 44 |
| 25 | 55 | 45 |
| 26 | 54 | 46 |
| 27 | 54 | 46 |
| 28 | 53 | 47 |
| 29 | 52 | 48 |
| 30 | 51 | 49 |
Chance of precipitation in September
Trieste gets around 170 mm of rain over 11.4 wet days in September. The line is the day-by-day chance of measurable precipitation.
Day to day, the chance of measurable rain averages around 39% and peaks near 44% on the wettest days.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain chance (%) | 36 | 37 | 37 | 37 | 37 | 37 | 37 | 38 | 38 | 38 | 39 | 39 | 39 | 39 | 39 | 40 | 40 | 40 | 40 | 40 | 40 | 40 | 40 | 41 | 41 | 41 | 42 | 43 | 43 | 44 |
| Rain chance (%) | |
|---|---|
| 1 | 36 |
| 2 | 37 |
| 3 | 37 |
| 4 | 37 |
| 5 | 37 |
| 6 | 37 |
| 7 | 37 |
| 8 | 38 |
| 9 | 38 |
| 10 | 38 |
| 11 | 39 |
| 12 | 39 |
| 13 | 39 |
| 14 | 39 |
| 15 | 39 |
| 16 | 40 |
| 17 | 40 |
| 18 | 40 |
| 19 | 40 |
| 20 | 40 |
| 21 | 40 |
| 22 | 40 |
| 23 | 40 |
| 24 | 41 |
| 25 | 41 |
| 26 | 41 |
| 27 | 42 |
| 28 | 43 |
| 29 | 43 |
| 30 | 44 |
Humidity in September
Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, September lands in the dry band about 41% of days. It rarely turns muggy — the humid and sticky bands barely register.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 26 | 27 | 28 | 29 | 30 | 31 | 31 | 32 | 33 | 33 | 34 | 35 | 36 | 37 | 39 | 40 | 42 | 44 | 46 | 47 | 49 | 51 | 52 | 54 | 54 | 55 | 56 | 56 | 57 | 57 |
| Comfortable (%) | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 33 | 34 | 35 | 35 | 35 | 35 | 35 | 34 | 34 | 34 | 33 | 32 | 32 | 31 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 |
| Humid (%) | 35 | 34 | 33 | 32 | 31 | 31 | 30 | 29 | 29 | 28 | 28 | 27 | 26 | 25 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 16 | 15 | 14 | 14 | 13 | 13 |
| Muggy (%) | 11 | 10 | 9 | 8 | 7 | 7 | 6 | 5 | 5 | 4 | 4 | 3 | 3 | 3 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | |
|---|---|---|---|---|
| 1 | 26 | 27 | 35 | 11 |
| 2 | 27 | 28 | 34 | 10 |
| 3 | 28 | 29 | 33 | 9 |
| 4 | 29 | 30 | 32 | 8 |
| 5 | 30 | 31 | 31 | 7 |
| 6 | 31 | 32 | 31 | 7 |
| 7 | 31 | 33 | 30 | 6 |
| 8 | 32 | 33 | 29 | 5 |
| 9 | 33 | 34 | 29 | 5 |
| 10 | 33 | 35 | 28 | 4 |
| 11 | 34 | 35 | 28 | 4 |
| 12 | 35 | 35 | 27 | 3 |
| 13 | 36 | 35 | 26 | 3 |
| 14 | 37 | 35 | 25 | 3 |
| 15 | 39 | 34 | 25 | 2 |
| 16 | 40 | 34 | 24 | 2 |
| 17 | 42 | 34 | 23 | 2 |
| 18 | 44 | 33 | 22 | 2 |
| 19 | 46 | 32 | 21 | 1 |
| 20 | 47 | 32 | 20 | 1 |
| 21 | 49 | 31 | 19 | 1 |
| 22 | 51 | 30 | 18 | 1 |
| 23 | 52 | 30 | 17 | 1 |
| 24 | 54 | 30 | 16 | 0 |
| 25 | 54 | 30 | 16 | 0 |
| 26 | 55 | 30 | 15 | 0 |
| 27 | 56 | 30 | 14 | 0 |
| 28 | 56 | 30 | 14 | 0 |
| 29 | 57 | 30 | 13 | 0 |
| 30 | 57 | 30 | 13 | 0 |
Wind in September
Winds average 10 km/h in September.
Across September, daily wind ranges from about 9 km/h on the calmest days to 10 km/h at its breeziest. It stays fairly steady from day to day.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| 1 | 9 | calm |
| 2 | 9 | calm |
| 3 | 9 | calm |
| 4 | 9 | calm |
| 5 | 9 | calm |
| 6 | 9 | calm |
| 7 | 9 | calm |
| 8 | 9 | calm |
| 9 | 10 | calm |
| 10 | 10 | calm |
| 11 | 10 | calm |
| 12 | 10 | calm |
| 13 | 10 | calm |
| 14 | 10 | calm |
| 15 | 10 | calm |
| 16 | 10 | calm |
| 17 | 10 | calm |
| 18 | 10 | calm |
| 19 | 10 | calm |
| 20 | 10 | calm |
| 21 | 10 | calm |
| 22 | 10 | calm |
| 23 | 10 | calm |
| 24 | 10 | calm |
| 25 | 10 | calm |
| 26 | 10 | calm |
| 27 | 10 | calm |
| 28 | 10 | calm |
| 29 | 10 | calm |
| 30 | 10 | calm |
Sunrise & sunset in September
Daylight runs from about 13 h 06 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.
Days shrink by about 96 minutes over September. Sunrise moves from 5:31 AM to 6:08 AM, and sunset from 6:38 PM to 5:41 PM.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 13.1 | 13.1 | 13.0 | 13.0 | 12.9 | 12.9 | 12.8 | 12.8 | 12.7 | 12.6 | 12.6 | 12.5 | 12.5 | 12.4 | 12.4 | 12.3 | 12.3 | 12.2 | 12.2 | 12.1 | 12.0 | 12.0 | 11.9 | 11.9 | 11.8 | 11.8 | 11.7 | 11.7 | 11.6 | 11.5 |
| Sunrise (AM) | 5:31 | 5:32 | 5:33 | 5:35 | 5:36 | 5:37 | 5:38 | 5:40 | 5:41 | 5:42 | 5:43 | 5:45 | 5:46 | 5:47 | 5:48 | 5:50 | 5:51 | 5:52 | 5:54 | 5:55 | 5:56 | 5:57 | 5:59 | 6:00 | 6:01 | 6:03 | 6:04 | 6:05 | 6:06 | 6:08 |
| Sunset (PM) | 6:38 | 6:37 | 6:35 | 6:33 | 6:31 | 6:29 | 6:27 | 6:25 | 6:23 | 6:21 | 6:19 | 6:17 | 6:15 | 6:13 | 6:11 | 6:09 | 6:07 | 6:05 | 6:03 | 6:01 | 5:59 | 5:57 | 5:55 | 5:53 | 5:51 | 5:49 | 5:47 | 5:45 | 5:43 | 5:41 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 13.1 | 5:31 | 6:38 |
| 2 | 13.1 | 5:32 | 6:37 |
| 3 | 13.0 | 5:33 | 6:35 |
| 4 | 13.0 | 5:35 | 6:33 |
| 5 | 12.9 | 5:36 | 6:31 |
| 6 | 12.9 | 5:37 | 6:29 |
| 7 | 12.8 | 5:38 | 6:27 |
| 8 | 12.8 | 5:40 | 6:25 |
| 9 | 12.7 | 5:41 | 6:23 |
| 10 | 12.6 | 5:42 | 6:21 |
| 11 | 12.6 | 5:43 | 6:19 |
| 12 | 12.5 | 5:45 | 6:17 |
| 13 | 12.5 | 5:46 | 6:15 |
| 14 | 12.4 | 5:47 | 6:13 |
| 15 | 12.4 | 5:48 | 6:11 |
| 16 | 12.3 | 5:50 | 6:09 |
| 17 | 12.3 | 5:51 | 6:07 |
| 18 | 12.2 | 5:52 | 6:05 |
| 19 | 12.2 | 5:54 | 6:03 |
| 20 | 12.1 | 5:55 | 6:01 |
| 21 | 12.0 | 5:56 | 5:59 |
| 22 | 12.0 | 5:57 | 5:57 |
| 23 | 11.9 | 5:59 | 5:55 |
| 24 | 11.9 | 6:00 | 5:53 |
| 25 | 11.8 | 6:01 | 5:51 |
| 26 | 11.8 | 6:03 | 5:49 |
| 27 | 11.7 | 6:04 | 5:47 |
| 28 | 11.7 | 6:05 | 5:45 |
| 29 | 11.6 | 6:06 | 5:43 |
| 30 | 11.5 | 6:08 | 5:41 |
Solar energy in September
Average shortwave solar energy reaching the ground each day in September, about 3.89 kWh/m².
For context, solar energy here swings from a low near 1.14 kWh/m² to a high of 6.28 kWh/m² in July across the year — September's 3.89 kWh/m² falls in the middle.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 4.7 | 4.6 | 4.5 | 4.5 | 4.5 | 4.4 | 4.3 | 4.3 | 4.2 | 4.2 | 4.1 | 4.1 | 4.0 | 3.9 | 3.9 | 3.8 | 3.8 | 3.7 | 3.7 | 3.6 | 3.6 | 3.5 | 3.5 | 3.4 | 3.4 | 3.3 | 3.3 | 3.2 | 3.1 | 3.1 |
| Level | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 4.7 | Bright |
| 2 | 4.6 | Bright |
| 3 | 4.5 | Bright |
| 4 | 4.5 | Bright |
| 5 | 4.5 | Bright |
| 6 | 4.4 | Bright |
| 7 | 4.3 | Bright |
| 8 | 4.3 | Bright |
| 9 | 4.2 | Bright |
| 10 | 4.2 | Bright |
| 11 | 4.1 | Bright |
| 12 | 4.1 | Bright |
| 13 | 4.0 | Bright |
| 14 | 3.9 | Moderate |
| 15 | 3.9 | Moderate |
| 16 | 3.8 | Moderate |
| 17 | 3.8 | Moderate |
| 18 | 3.7 | Moderate |
| 19 | 3.7 | Moderate |
| 20 | 3.6 | Moderate |
| 21 | 3.6 | Moderate |
| 22 | 3.5 | Moderate |
| 23 | 3.5 | Moderate |
| 24 | 3.4 | Moderate |
| 25 | 3.4 | Moderate |
| 26 | 3.3 | Moderate |
| 27 | 3.3 | Moderate |
| 28 | 3.2 | Moderate |
| 29 | 3.1 | Moderate |
| 30 | 3.1 | Moderate |
Is September a good time to visit Trieste?
Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).
September is a reasonable time to visit Trieste for sightseeing.
What to pack for Trieste in September
From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In September, Trieste sees daytime highs around 21°C and nights near 15°C. Worth packing: rain gear. About 11 days see rain.
Sea temperature near Trieste in September
The nearest coast averages about 23°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea offshore is warmest in August at about 25°C and coldest in February near 10°C.
It's comfortable for a long swim from May 31 to Oct 9 — about 4.3 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 11 | 10 | 10 | 13 | 18 | 23 | 25 | 25 | 23 | 19 | 16 | 13 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Cool | Refreshing | Warm | Warm | Refreshing | Cool | Cool | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 11 | Bracing |
| Feb | 10 | Bracing |
| Mar | 10 | Bracing |
| Apr | 13 | Bracing |
| May | 18 | Cool |
| Jun | 23 | Refreshing |
| Jul | 25 | Warm |
| Aug | 25 | Warm |
| Sep | 23 | Refreshing |
| Oct | 19 | Cool |
| Nov | 16 | Cool |
| Dec | 13 | Bracing |
UV index in Trieste in September
Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Trieste peaks around July 15 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 2 | 4 | 7 | 7 | 8 | 8 | 7 | 5 | 3 | 2 | 1 |
| Level | Low | Moderate | Moderate | High | High | Very high | Very high | Very high | Moderate | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 2 | Moderate |
| Mar | 4 | Moderate |
| Apr | 7 | High |
| May | 7 | High |
| Jun | 8 | Very high |
| Jul | 8 | Very high |
| Aug | 7 | Very high |
| Sep | 5 | Moderate |
| Oct | 3 | Moderate |
| Nov | 2 | Low |
| Dec | 1 | Low |
Air quality in Trieste in September
Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.
Air quality in Trieste is worst in January — around 16 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (September, 9 µg/m³).
Seasonal pattern from CAMS reanalysis, scaled to Trieste's WHO annual average of 12 µg/m³.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 16 | 14 | 14 | 13 | 11 | 12 | 12 | 10 | 9 | 10 | 10 | 13 |
| Level | Moderate | Moderate | Moderate | Moderate | Good | Good | Good | Good | Good | Good | Good | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 16 | Moderate |
| Feb | 14 | Moderate |
| Mar | 14 | Moderate |
| Apr | 13 | Moderate |
| May | 11 | Good |
| Jun | 12 | Good |
| Jul | 12 | Good |
| Aug | 10 | Good |
| Sep | 9 | Good |
| Oct | 10 | Good |
| Nov | 10 | Good |
| Dec | 13 | Moderate |
Where is Trieste?
Trieste sits at 45.6°N, 13.8°E, 2 m above sea level, in Italy. The nearest listed city is Koper, 12 km away.
Topography around Trieste
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Trieste.
Within 3 km, the terrain around Trieste has significant variations in elevation — a maximum elevation change of 451 m around an average of 72 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 779 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,524 m.
The land around Trieste is covered by artificial surfaces (41%), trees (31%) and water (27%) within 3 km, trees (50%) and water (32%) within 16 km, and trees (52%) and water (23%) within 80 km.
Italy travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type C / F / L
- 230 V · 50 Hz
- Prices
- ≈ 69% of US
- price level, 2025
- GDP per capita
- $43,309
- 2025
- Happiness
- 6.6 / 10
- World Happiness, 2025
- Safe drinking water
- 97%
- of population, 2024
- Homicide rate
- 0.6
- per 100k, 2023
- Road deaths
- 5.3
- per 100k/yr, 2019
- Income group
- High
- World Bank
- English
- Moderate
- EF EPI 513
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Trieste (45.6495°, 13.7768°, elevation 2 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).