Photo: Jeangagnon · CC BY-SA 4.0A flood study covers Brossard: 1 on the national inventory, the newest from Gouvernement du Québec
Little of the land around Brossard has burned: 0.1% within 25 km since 1986, or 0.002% a year. Seismic risk runs high: $0.22 of expected damage per $1,000 of buildings a year, the typical town $0.030. About as many homes carry radon around Brossard as elsewhere, 8.2% over the guideline where the typical town has 6.6%. Hazard risk gives Brossard a grade of C−, from earthquakes and radon alone.
What stands out about Brossard’s hazards
Four national sources, each read for Brossard: earthquakes, radon, past fires and flood studies.
What Brossard faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Brossard: C−
Two inputs always count for Brossard, earthquakes and radon; the third, wildfire, counts only against a town.
Its place: #381 of 507 in Quebec and #2,360 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. Small fires and grass fires are largely missing from the national burned-area record.
Wildfire is rare near Brossard: 0.1% of the land within 25 km burned since 1986, 0.3% within 5 km
Past fire around Brossard’s homes, from the national burned-area record, with the fuel within 5 km.
Around Brossard fire takes 0.002% of the land in a typical year, the typical Canadian town 0.000%, which is low.
Forest fuel is scarce around Brossard: 0.3% of the land within 5 km, 0.5% 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 513
Mistissini burns fastest in Quebec at 0.31% a year; Brossard, at 0.002%, ranks 35th of 513.
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.
Beside 2,610 Canadian towns, Brossard reads low, with 92% of them; only 7.5% rank 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.
Brossard is on the flood map inventory: 1 study, by Gouvernement du Québec
What Canada’s Flood Map Inventory lists for Brossard: who studied flooding and where to see their maps.
For Brossard the inventory points to Gouvernement du Québec’s 2006 study, whose map is the one to check.
| Study | By | Year | Status |
|---|---|---|---|
| Prairie-Longueuil | Gouvernement du Québec | 2006 | final |
Towns with a flood study on file
Flood maps are thinner in Quebec, 45% of towns against 58% nationally, but Brossard has one.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Listed, not scored: a flood study proves a map exists, not that Brossard floods.
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.
Earthquakes cost buildings in Brossard $0.22 per $1,000 a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
At $0.22 per $1,000, Brossard carries roughly 7.4 times the typical Canadian town’s earthquake risk ($0.030).
Shaking damage a year per $1,000 of building value
At $0.22, Brossard is above the typical town in Quebec ($0.14); La Pocatière has the most 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.
Only 7.4% of Canada’s 2,611 towns expect more shaking damage than Brossard.
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).
The loss is to Brossard’s buildings alone, from ground shaking; infrastructure and secondary hazards are left out.
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 Brossard: 8.2% of area homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline.
Brossard’s area sits close to the typical Canadian town: 8.2% over the guideline, against 6.6%. Behind radon tests sits data gathered across the Monteregie health region, with Brossard one part of it.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Brossard, 8.2% of tests topped the guideline, about the same as the typical town in Quebec (8.2%).
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Brossard is in the 5–10% band with 37% of Canada’s 2,611 towns; 26% have more.
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.
Basements, soil and how a house is sealed decide its radon, so in Brossard only a test can say.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Brossard
Alerts for Brossard 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 Brossard 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 Brossard
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Brossard | Low | $0.22 | 8.2% | Yes |
| Vieux Greenfield Park 10,998 · 3.6 km | Low | $0.23 | 8.2% | None listed |
| Iberville 17,988 · 3.6 km | Low | $0.23 | 8.2% | None listed |
| Nouveau Greenfield Park 6,199 · 3.7 km | Low | $0.23 | 8.2% | None listed |
| Laflèche 19,706 · 4.7 km | Low | $0.23 | 8.2% | None listed |
| Maricourt 14,407 · 4.8 km | Low | $0.23 | 8.2% | None listed |
| La Prairie 27,159 · 5.1 km | Low | $0.21 | 8.2% | Yes |
None of the places around has more fire nearby than Brossard (low); Vieux Greenfield Park comes closest (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Brossard faces
What to do about the hazards Brossard faces, and what to ask before you buy.
- 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
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Brossard’s homes burned each year from 1986 to 2025, past fire rather than a forecast, and it can only lower Risk.
- Radon is a survey. Radon figures pool the survey’s home tests by area: postal areas once their boundaries arrive, the 2007 health region around Brossard until then.
- Flood studies aren’t flood zones. Flood studies cover areas of every size, which is why the page lists them for Brossard without grading them.
- 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 Brossard’s.
Questions about flooding and hazards in Brossard
How big is the earthquake risk in Brossard?
NRCan’s model expects shaking to cost buildings in Brossard $0.22 a year for every $1,000 of their value, on average over many years.
Is radon a problem in Brossard?
In Health Canada’s survey, 8.2% of 110 homes tested in Brossard’s area were above 200 Bq/m³, though only a test tells you about one house.
How is Brossard’s Hazard risk Grade worked out?
Hazard risk gives Brossard C−, weighing earthquakes and radon and counting wildfire only against it.
Does Brossard flood?
A flood study covers Brossard on Canada’s Flood Map Inventory; open the owner’s map to check a street, since flood isn’t graded.
Is Brossard at risk of wildfire?
Less than most of Canada: 0.1% of the land within 25 km of Brossard has burned since 1986, the last in 2025, a low band that leaves Risk alone.
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).