Climate and air in Aosta
Alpine valley-floor climate, among the driest in Italy: cold winters with temperature inversions and snow, mild breezy summers, plenty of sun. The föhn brings clear, mild days. Generally good air, with few days above the PM10 limit; ARPA VdA also monitors the steelworks area.
Sections: Seasons · Rainfall · Temperatures · Air quality · Environmental hazards
Seasons
Aosta lies in an inner-Alpine basin sheltered from Atlantic and Mediterranean weather systems: rainfall is low for an Alpine town and sunshine is frequent. Winter is cold, with regular night frosts and snow in town on a few occasions a year; on settled days the temperature inversion keeps cold air and haze on the valley floor while above a thousand metres it is clear. The föhn, a warm dry wind descending from the side valleys, can raise temperatures by many degrees in a few hours.
Summer is mild, rarely muggy, with afternoon valley breezes and thunderstorms over the peaks; nights stay cool. Spring and autumn are short. Those living on the hillside (Signayes, Porossan) get more sun and less fog in winter than the valley floor.
Air quality and hazards
Air quality is among the best of Italian provincial capitals: exceedances of the daily PM10 limit are few and concentrated on winter inversion days, when wood heating in the villages and traffic add up. ARPA Valle d'Aosta runs the measuring stations in town and a specific monitoring of dust and metals in the area of the Cogne steelworks, whose data are published online.
Natural hazards are the Alpine ones: avalanches and landslides in the side valleys, floods of the Dora Baltea in very wet autumns (the October 2000 flood is the reference), snow and ice on the roads in winter. The regional Centro funzionale issues the alert bulletins.
Missing: rain_days_year
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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