Smoke forecast
Where the smoke over Boston was, and where the model sends it next. Scrub back 12 hours or forward 48. Every hour shown is a model estimate, not a measurement.
The scale is anchored to visibility, because that is the one reading you can take yourself without trusting a model. Distances are approximate.
From Castle Island the downtown skyline is sharp three miles northwest, and the Blue Hills read clean on the southern horizon about ten miles out.
The Blue Hills have gone. Downtown still reads from Castle Island but has flattened, and the harbor islands have lost their trees.
The Prudential and 200 Clarendon still mark the skyline from South Boston, three miles off, but everything behind them has merged.
From the Harborwalk the near towers hold while the tops of the tallest buildings, a bit over a mile away, fade into the haze.
The top of 200 Clarendon goes. From the waterfront you can lose the far side of the harbor entirely.
Boston is at the far downwind end of the Quebec corridor. Fires in Quebec and Ontario sit north and northwest, and their smoke reaches New England on northerly flow after a day or more aloft, which means it often arrives as a high haze before descending. Boston also catches smoke from Nova Scotia and New Brunswick on the rarer easterly setups.
June 2023 is the event that changed local awareness, when Quebec smoke pushed Boston into unhealthy air for multiple days and the sun went orange in the middle of the afternoon.
The verdict at the top of this page answers that for Boston specifically. Boston sits at the far end of the Quebec corridor, and distance changes the shape of the problem: smoke arriving here has usually spent a day or more aloft, so it often shows up as a high haze overhead before it is anything you are breathing. Everything shown is a model estimate rather than a measurement at your address.
That is the headline answer above: the clear time, the first stretch of at least six straight hours below the Hazy threshold. Being far downwind makes it a steadier answer than it is in Toronto. An aged plume is broad rather than sharp, so it comes and goes slowly. The trade is that it also lingers, which is what June 2023 looked like here: multiple days rather than one bad afternoon.
Usually Quebec or Ontario, north and northwest, after a day or more in transit. There is a second, rarer case worth knowing about that no other page on this site has: on easterly setups Boston catches smoke from Nova Scotia and New Brunswick, coming in off the water rather than down from the interior. June 2023 is the event that changed local awareness, when the sun went orange in the middle of the afternoon.
Quebec and Ontario for most events, arriving on northerly flow after a day or more aloft. Nova Scotia and New Brunswick supply the rarer easterly version. Toronto is the useful upwind check on the common case, sitting under the same Quebec plumes roughly two days earlier and getting them thick. Run the timeline backward on the map and the transit shows.
The five-day strip above gives the day-by-day read and the timeline covers forty-eight hours hour by hour. Boston gets the longest warning of any city on this corridor, because the smoke has to cross Ontario and New York State first, so the five-day view here is worth more than it is upwind. Forecasts are sharpest one to two days out and the page shows where the models disagree.
The Blue Hills on the southern horizon are the far check at about ten miles from Castle Island, and they go first. Then the harbor islands losing their trees while downtown flattens. Then whether the Prudential and 200 Clarendon still mark the skyline from South Boston or everything behind them has merged. When the top of 200 Clarendon goes and the far side of the harbor disappears from the waterfront, that is the bottom.
Where Boston's smoke usually shows up first, and the places that share its air.
Quebec and Ontario smoke reaches Toronto thick and unaged, roughly two days before the same plume arrives over New England as a high haze.
Most smoke in the eastern half of the continent is Canadian, and it is old by the time it arrives.
Smokeshow is for informational and educational purposes only. It is not health, medical, or safety advice. Forecasts are model estimates and can be wrong, sometimes by a lot. Descriptions of what you might smell, see, or feel are generalizations, not predictions about your body. For decisions about your health, outdoor activity, or air quality safety, rely on official sources like AirNow.gov, the National Weather Service, and your local health authorities, and talk to a medical professional about your own situation.