Climate: Bora, sea and clean air
Maritime climate with mild but windy winters due to the Bora, hot humid summers and rainfall concentrated in autumn. Air quality is among the best of the northern capitals thanks to constant ventilation.
Sections: Seasons · Rainfall · Temperatures · Air quality · Environmental hazards
The Bora
The Bora is a katabatic wind from the east-north-east that descends from the Karst towards the gulf: it blows in any season but most often and most strongly between November and March, with gusts that regularly exceed 100 km/h and in exceptional episodes have reached far higher values. The regional meteorological observatory (OSMER, ARPA FVG) publishes forecasts and warnings; on days of strong Bora the municipality may close parks and the Molo Audace pier, and ropes anchored to the walls are still in place along some uphill streets in the centre. The "clear" Bora brings crisp skies and dry cold; the "dark" Bora comes with rain or snow.
Seasons and temperatures
The sea and the low altitude make winters milder than in Udine or the Veneto plain, with snow rare in the city and more frequent in Opicina, 300 metres higher. Summer is hot and humid, tempered by the sea breeze; the Karst plateau offers a few degrees less. Rainfall is abundant in autumn, with intense downpours; rainy days per year are more numerous than in the Po-valley cities, though without their fog.
Air quality
Constant ventilation keeps pollutants low: exceedances of the daily PM10 limit in Trieste are few compared with the Po valley. The Servola industrial area, with the former steelworks whose hot section is now closed, has historically been the main point of concern; monitoring is by ARPA FVG.
Data
Sources
Updated: 2026-10-14
Updated: 2026-10-14
Updated: 2026-10-14
Reviewed: 10/20/2026 · by piero.avolio · rev. 1 · Period: → 2027-10-31
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