US air quality and smoke forecast

PM_2.5 observations and smoke forecasts (µg/m³)

Observations and NowCast are total PM_2.5 — wildfire smoke plus every other source — as regulatory monitors measure it, and FireWork models that same total. FireSmoke and HRRR-Smoke estimate the wildfire contribution only, so they read lower than the monitors whenever other sources matter. The optional map plume surfaces are likewise fires-only.

Stated times are local to the selected station and mark the end of each measurement hour, as agency displays do. FireSmoke is UBC's BlueSky dispersion model; FireWork is ECCC's operational chemistry model; HRRR-Smoke is NOAA's 3 km smoke model. NowCast is the US EPA's smoke-responsive weighted average of recent hours; the shaded bands are US EPA AQI category thresholds (24-h basis, 2024 revision), which apply to NowCast — not to single hourly readings. The dashed line marks now; forecasts extend beyond it.