Montreal air quality
Quebec, Canada · Live AQI and hourly forecast for the next 5 days · updated Sat 20:00 local time
Good
Great air. A perfect time to be outside.
- Next 24 hours
- 30–43US AQI, highest around Sun 06:00
- Best time outside
- Sun 16:00–19:00US AQI about 30
- PM2.5 vs WHO guideline
- 0.3×4.9 µg/m³ over 24 h, guideline 15
- Cigarette equivalent
- ≈ 0.2 a dayBerkeley Earth rule of thumb
- European AQI
- Fairlevel 2 of 6
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Pollutants in Montreal right now
| Pollutant | Now | Next 24 h vs WHO | US AQI band |
|---|---|---|---|
| Fine particles (PM2.5) | 7.5 µg/m³ | 0.3× | Good |
| Coarse particles (PM10) | 7.6 µg/m³ | 0.1× | Good |
| Nitrogen dioxide (NO2) | 15 µg/m³ | 0.3× | Good |
| Ozone (O3) | 55 µg/m³ | 0.6× | Good |
| Sulphur dioxide (SO2) | 3.6 µg/m³ | 0.1× | Good |
| Carbon monoxide (CO) | 174 µg/m³ | 0.0× | Good |
| Desert dust | 0 µg/m³ | ||
| Smoke and haze (aerosol optical depth) | 0.09 | ||
| UV index | 0.0 |
“Next 24 h vs WHO” compares the forecast with the World Health Organization’s 2021 guideline levels: 24-hour means of 15 µg/m³ for PM2.5, 45 for PM10, 25 for NO2, 40 for SO2 and 4 mg/m³ for CO, and 100 µg/m³ over 8 hours for ozone. Above 1× is above the guideline.
Next 48 hours
Hourly US AQI. Highest 43 around Sun 06:00, lowest 21 around Mon 08:00.
5-day air quality forecast for Montreal
Daily range of the hourly US AQI, from lowest to highest, on a scale of 0 to 150.
| Day | US AQI | At worst | PM2.5 avg | |
|---|---|---|---|---|
| Sat 26 Sept | 41–56 | 7.5 | ||
| Sun 27 Sept | 26–43 | 4.4 | ||
| Mon 28 Sept | 21–25 | 3.6 | ||
| Tue 29 Sept | 20–43 | 8.6 | ||
| Wed 30 Sept | 48–60 | 11 |
Common questions about the air in Montreal
Is the air in Montreal safe today?
Yes. Right now the US AQI in Montreal is 42, which counts as good. Great air. A perfect time to be outside.
When is the best time to be outside in Montreal?
Sun 16:00–19:00. That is the cleanest stretch in the next 24 hours, with the US AQI averaging about 30. The worst hour is around Sun 06:00, at 43.
What is the main pollutant in Montreal?
Fine particles (PM2.5). It drives the index right now, at 7.5 µg/m³. Tiny particles from combustion, fires and dust that reach deep into the lungs. The main driver of AQI worldwide.
How does Montreal's air compare with the WHO guideline?
Within the guideline. Over the next 24 hours PM2.5 averages about 4.9 µg/m³, against the World Health Organization's 24-hour guideline of 15 µg/m³. The other pollutants stay within their guideline levels.
How many cigarettes is a day of Montreal's air?
About 0.2 cigarettes. Over the next 24 hours PM2.5 averages about 4.9 µg/m³. By Berkeley Earth's rule of thumb, 22 µg/m³ breathed for a day is roughly one cigarette.
Will air quality in Montreal improve this week?
Monday looks cleanest. Its AQI peaks at 25, against 60 on Wednesday, the worst day in the forecast.
Measured near Montreal
| Station | PM2.5 µg/m³ | Measured |
|---|---|---|
| St-Dominique AirNow, reference monitor | 8.1 | Sat 18:00 |
| York-Roberval AirNow, reference monitor | 7.6 | Sat 18:00 |
| Molson AirNow, reference monitor | 6.6 | Sat 18:00 |
Air quality near Montreal
- Ottawa 166 km W
- Boston 403 km SE
- Toronto 504 km W
- New York 534 km S
- Philadelphia 631 km S
- Washington, D.C. 787 km S
About this forecast
Forecast from CAMS global via Open-Meteo: the Copernicus Atmosphere Monitoring Service (CAMS) model at about 40 km resolution (10 km inside Europe), refreshed twice a day. Models smooth out street-level peaks, so busy roads and industrial sites can be worse than shown; ground stations, where there are any nearby, show what monitors actually measure. The US AQI follows the US EPA scale and the European AQI the EEA bands. Readings for 45.50°N, 73.57°W, updated 2026-09-27 00:00 UTC.