Photo: CanadianPhotographer · CC0Flood mapping exists for Montréal: 2 on record, latest by Communauté métropolitaine de Montréal
Burn scars are few around Montréal, with 0% of the land within 25 km touched by fire since 1986 (0.001% a year). Shaking is a bigger worry than in most places, at $0.20 a year per $1,000 of building value ($0.030 typical). About as many homes carry radon around Montréal as elsewhere, 6.8% over the guideline where the typical town has 6.6%.
What stands out about Montréal’s hazards
Four national sources, each read for Montréal: earthquakes, radon, past fires and flood studies.
What Montréal faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Montréal isn’t graded for hazard risk yet
Seismic risk and radon set Montréal’s grade, wildfire can drag it down, and flood mapping stays out of it.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. The radon share rests on 74 home tests in the survey area, so a few homes move it. Small fires and grass fires are largely missing from the national burned-area record.
Wildfire is rare near Montréal: 0% of the land within 25 km burned since 1986, 0% within 5 km
Past fire around Montréal’s homes, from the national burned-area record, with the fuel within 5 km.
Low: the land around Montréal burns at 0.001% a year, where the typical Canadian town sees 0.000%.
Little near Montréal’s homes can carry a forest fire; only 0.4% of the land within 5 km is forest fuel, and 2.5% within 25 km.
Shares of land within 5 and 25 km of populated blocks: burned at least once in 1986–2025 (CWFIS burned-area composite), forest fuel and grass (fire behaviour fuel types, 2026, 250 m grid).
Burn rate a year, towns in Quebec · highest of 514
Montréal sits mid-table in Quebec: 136th of 514 towns, at 0.001% a year, well behind Mistissini (0.31%).
Each bar: the yearly average share of land within 25 km of a town’s homes that burned, 1986–2025 (CWFIS); the seven highest towns of 2,500 people or more.
Montréal is in the low band with 92% of Canada’s 2,610 towns; 7.5% sit in moderate or higher.
Bands of the yearly burn rate: low under 0.05%, moderate under 0.25%, high under 1%, very high 1% or more; towns of 2,500 people or more.
Fire danger and active fires (CWFIS)
Canadian Wildland Fire Information System: National Burned Area Composite 1986–2025 and fire behaviour fuel types (2026), Natural Resources Canada. Measured within 25 km and 5 km of each populated dissemination area; past fire, not a forecast.
Flooding around Montréal is mapped in 2 studies, the newest by Communauté métropolitaine de Montréal
What Canada’s Flood Map Inventory lists for Montréal: who studied flooding and where to see their maps.
The newest of 2 studies covering Montréal is Communauté métropolitaine de Montréal’s, from 2008; open its map to see the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Montréal-Argenteuil-Deux-Montagnes-Vaudreuil-Soulanges | Communauté métropolitaine de Montréal | 2008 | final |
| Moulins-Thérèse-De-Blainville-Deux-Montagnes-Laval | Gouvernement du Québec | 2006 | final |
Towns with a flood study on file
Only 45% of towns in Quebec have a flood study, short of Canada’s 58%; Montréal is one of them.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood studies don’t enter the grade; they are listed so you can open the official map for Montréal.
The inventory’s own caution (NRCan): “The Canada Flood Map (CFM) does not include every flood hazard map in Canada and may be incomplete or contain inaccuracies. It should not be relied upon as the official source of flood mapping information. Furthermore, if a map appears to be missing, this does not necessarily mean that the area has never been mapped. For the official version of a map, updated information, or confirmation of applicable regulations, please contact the local authority responsible for flood mapping.”
Natural Resources Canada, Canada Flood Map Inventory; links go to each study’s owner.
High seismic risk in Montréal: $0.20 per $1,000 of buildings a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Roughly 6.7 times the typical $0.030: Montréal’s $0.20 marks real seismic exposure.
Shaking damage a year per $1,000 of building value
Above the middle in Quebec: Montréal’s $0.20 against a median of $0.14, with La Pocatière highest at $0.48.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Few of Canada’s 2,611 towns face more earthquake damage than Montréal: 8.5% of them.
Each column: the share of Canada’s towns of 2,500 people or more in that range of yearly loss per $1,000 (NRCan, 2022).
Roads, pipes and bridges aren’t in Montréal’s figure, nor landslides or tsunami: it is buildings and shaking.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Some radon around Montréal: 6.8% of area homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline.
Around Montréal, 6.8% of tested homes topped the guideline, near the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
The typical town in Quebec has 8.2% over 200 Bq/m³; Montréal’s area has 6.8%, much the same.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
37% of Canada’s 2,611 towns share Montréal’s band of 5 to 10%; 26% sit higher.
Each bar: the share of Canada’s towns of 2,500 people or more whose survey area had that share of tests over 200 Bq/m³.
The survey sampled homes around Montréal; it can’t tell you your basement’s level.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Area behind the radon tests figures: the Montreal health region
Weather and fire alerts for Montréal
Alerts for Montréal come from Environment and Climate Change Canada and, for emergencies, Alert Ready.
| Alert | What it means |
|---|---|
| Warning | Severe weather is happening or about to: act now. |
| Watch | Conditions favour severe weather: be ready. |
| Advisory | Weather that is less severe but could disrupt the day. |
| Special weather statement | Unusual weather worth knowing about. |
| Special air quality statement | Poor air, often wildfire smoke. |
Evacuation orders for Montréal come from the municipality or the province, while CWFIS maps fire danger every day.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Montréal
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Montréal | Low | $0.20 | 6.8% | Yes |
| Saint-Édouard 16,771 · 0.7 km | Low | $0.20 | 6.8% | None listed |
| Parc-Jarry 15,699 · 1.1 km | Low | $0.20 | 6.8% | None listed |
| Parc-Extension 29,066 · 1.2 km | Low | $0.20 | 6.8% | None listed |
| Crémazie 29,907 · 1.4 km | Low | $0.20 | 6.8% | None listed |
| Père-Marquette 19,702 · 1.5 km | Low | $0.20 | 6.8% | None listed |
| Outremont 24,629 · 1.7 km | Low | $0.20 | 6.8% | None listed |
The fire record around Saint-Édouard is a touch heavier than Montréal’s, but the band is the same: low (here low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Montréal faces
Practical steps for Montréal’s hazards, most pressing first.
- Test for three months in winter.
- Over 200 Bq/m³: fix it.
- Kits are cheap; pros test too.
- Never drive through floodwater.
- Move papers and medicines upstairs.
- Ask whether your street is mapped.
- Drop, cover and hold on.
- Strap the water heater down.
- Keep 72 hours of supplies.
- Has it had a radon test?
- Check the address on the flood map.
- Are flood and wildfire insured?
- Is earthquake cover included?
What this data can and can’t tell you
- Earthquakes are modelled. Shaking damage is modelled from the ground, the buildings and the odds of each quake, and published for whole subdivisions such as Montréal’s.
- Flood studies aren’t flood zones. NRCan’s inventory says where flood mapping exists, not where water goes; the map’s owner is the authority for Montréal.
- Radon is a survey. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Montréal is its health region’s, the survey’s design unit.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Montréal’s homes burned each year from 1986 to 2025, past fire rather than a forecast, and it can only lower Risk.
Questions about flooding and hazards in Montréal
Does Montréal flood?
There is flood mapping for Montréal on the national inventory, each study linked to its owner’s map, none of them graded.
Is radon a problem in Montréal?
The area’s survey found 6.8% of 74 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Montréal.
Is Montréal at risk of wildfire?
Some, but Montréal’s low band (0% of nearby land burned since 1986, latest 2025) is short of the level that counts.
How is Montréal’s Hazard risk Grade worked out?
Not so far for Montréal; its Hazard risk letter waits for Canada’s grading run.
How big is the earthquake risk in Montréal?
In NRCan’s seismic model, Montréal’s buildings lose $0.20 per $1,000 of value in an average year.
Seismic risk: Natural Resources Canada. Radon: Health Canada. Wildfire: Canadian Wildland Fire Information System. Flood studies: Natural Resources Canada, Canada Flood Map Inventory. Contains information licensed under the Open Government Licence – Canada.
Sources: NRCan, Canada’s Seismic Risk Model 2022 · Health Canada, Cross-Canada Survey of Radon Concentrations in Homes · CWFIS, National Burned Area Composite and FBP fuel types · NRCan, Canada Flood Map Inventory. Under the Statistics Canada Open Licence.
Adapted from Statistics Canada (Census of Population 2021, population estimates 2025, 2021 census boundaries) under the Statistics Canada Open Licence; this does not constitute an endorsement by Statistics Canada. Neighbourhood names in some cities © OpenStreetMap contributors (ODbL).