9 µg/m³ NowCast — Good on the US EPA scale — the median across 2 monitors in Lethbridge - Taber - Milk River. Individual monitors run 3–14 µg/m³, highest at Lethbridge. Environment Canada's Air Quality Health Index nearby is 2.
16 µg/m³ measured at Lethbridge, 3 km away, at Aug 07, 10:00AM.
Air quality is good — ideal for outdoor activities.
Forecasts show smoke increasing, peaking near 52 µg/m³ within the next 48 hours.
Smoke is expected to arrive around Aug 07, 6:00PM and clear by about Aug 08, 6:00AM.
1–3 low · 4–6 moderate · 7–10 high · 10+ very high · Forecast squares are Environment Canada's official AQHI period maximums.
● Observed — hourly median · ● FireSmoke · ● FireWork · ● HRRR · ▬ range across monitors
Background bands (US EPA AQI, 24-h basis): ■ Good · ■ Moderate · ■ Unhealthy for Sensitive Groups · ■ Unhealthy
| Model | Peak PM2.5 | Peak around |
|---|---|---|
| FireSmoke (UBC BlueSky) | 21 µg/m³ | Aug 07, 9:00PM |
| FireWork (ECCC) | 35 µg/m³ | Aug 08, 1:00AM |
| HRRR-Smoke (NOAA, 3 km) | 52 µg/m³ | Aug 08, 2:00AM |
Model values are for the ~10 km grid cell nearest Lethbridge; 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.
Smoke is overhead, not in the air you breathe.
● 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
20-day record · 2 nearby monitors
| Model | Typical error | Tendency |
|---|---|---|
| FireWork | 14.4 µg/m³ | reads low 12.8 |
| FireSmoke | 19.6 µg/m³ | reads low 14.0 |
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 Lethbridge — hourly observations, NowCast and both model forecasts.
See the Alberta-wide forecast — every monitor, ranked →
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