8 µg/m³ measured at Thunder Bay, 3 km away, at Aug 06, 2:00PM. The NowCast smoke average is 9 µg/m³ — Good on the US EPA scale. Environment Canada's Air Quality Health Index nearby is 2.
Air quality is good — ideal for outdoor activities.
Forecasts show smoke increasing, peaking near 14 µg/m³ within the next 48 hours.
No significant smoke is expected in the next 48 hours.
1–3 low · 4–6 moderate · 7–10 high · 10+ very high · Forecast squares are Environment Canada's official AQHI period maximums.
● Observed (hourly) · ● FireSmoke · ● FireWork · ● HRRR
Background bands (US EPA AQI, 24-h basis): ■ Good · ■ Moderate
| Model | Peak PM2.5 | Peak around |
|---|---|---|
| FireSmoke (UBC BlueSky) | 2 µg/m³ | Aug 07, 1:00AM |
| FireWork (ECCC) | 14 µg/m³ | Aug 07, 1:00PM |
| HRRR-Smoke (NOAA, 3 km) | 3 µg/m³ | Aug 06, 6:00PM |
Model values are for the ~10 km grid cell nearest Thunder Bay; the two models are independent and often disagree — treat the higher value as the cautious planning number.
Observations and NowCast are total PM2.5 — wildfire smoke plus every other source — as regulatory monitors measure it, and FireWork models that same total. FireSmoke is a smoke-dispersion model: it estimates the wildfire contribution only, so it reads lower than the monitors whenever other sources matter. The map's optional plume layer is likewise fires-only.
Little smoke at the surface or overhead.
● At the ground · ● Overhead (if mixed down)
Overhead smoke dims the sun but is not what you breathe. The dashed line shows the surface level if the whole column mixed through the boundary layer — a worst case, not a forecast · Data: NOAA HRRR-Smoke
19-day record · 1 nearby monitors
| Model | Typical error | Tendency |
|---|---|---|
| FireSmoke | 17.3 µg/m³ | reads low 16.6 |
| FireWork | 18.3 µg/m³ | reads low 15.7 |
Mean absolute error and average tendency in µg/m³, from forecasts verified 0–6 hours ahead at monitors within 50 km. A short-range record, not a measure of how far ahead a model stays reliable. FireSmoke and HRRR model wildfire smoke only, so they read below the monitors whenever other sources of PM2.5 matter.
Open the live chart for Thunder Bay — hourly observations, NowCast and both model forecasts.
See the Ontario-wide forecast — every monitor, ranked →
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