Photo: Andre Carrotflower · CC BY-SA 4.0Flood mapping exists for Saint-Jérôme: 3 on record, latest by Gouvernement du Québec
Little of the land around Saint-Jérôme has burned: 0.1% within 25 km since 1986, or 0.001% a year. Earthquakes add more: NRCan’s model puts building losses at $0.15 a year per $1,000 of value, against $0.030 for the typical town. More homes than usual carry radon here, 10% over the guideline where the typical town has 6.6%. Saint-Jérôme grades C− for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Saint-Jérôme’s hazards
Four national sources, each read for Saint-Jérôme: earthquakes, radon, past fires and flood studies.
What Saint-Jérôme faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Saint-Jérôme: C−
Risk averages earthquakes and radon; wildfire joins only where it pulls the average down, so a town like Saint-Jérôme with little fire nearby would get no credit for it.
Its place: #422 of 507 in Quebec and #2,413 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. Only 78 homes were tested in the survey area, so the radon share is rough. Small fires and grass fires are largely missing from the national burned-area record.
Little of the land around Saint-Jérôme has burned: 0.1% within 5 km, 0.1% within 25 km since 1986
Past fire around Saint-Jérôme’s homes, from the national burned-area record, with the fuel within 5 km.
Saint-Jérôme burns at 0.001% a year, low against 0.000% for the typical Canadian town.
Near or far, forest fuel covers a similar share around Saint-Jérôme: 21% within 5 km and 18% 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
At 0.001% a year, Saint-Jérôme ranks 136th of the 513 towns in Quebec; Mistissini leads at 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.
Beside 2,610 Canadian towns, Saint-Jérôme 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.
3 flood studies cover Saint-Jérôme, the newest from Gouvernement du Québec
What Canada’s Flood Map Inventory lists for Saint-Jérôme: who studied flooding and where to see their maps.
The newest of 3 studies covering Saint-Jérôme is Gouvernement du Québec’s, from 2005; open its map to see the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Prévost-St-Jérôme | Gouvernement du Québec | 2005 | final |
| St-Jérôme | Gouvernement du Québec | 2004 | final |
| Lachute-St-Jérôme | Gouvernement du Québec | 1992 | final |
Towns with a flood study on file
Flood maps are thinner in Quebec, 45% of towns against 58% nationally, but Saint-Jérôme has one.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Mapping around Saint-Jérôme goes back to the 1990s and peaks in the 2000s, with 2 of its 3 studies.
Study dates as the NRCan inventory lists them, one count per study touching Saint-Jérôme.
Listed, not scored: a flood study proves a map exists, not that Saint-Jérôme 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 Saint-Jérôme $0.15 per $1,000 a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
The typical town loses $0.030 a year to shaking; Saint-Jérôme loses $0.15, 4.9 times as much.
Shaking damage a year per $1,000 of building value
Typical for its province: Saint-Jérôme at $0.15 beside a median in Quebec of $0.14, with La Pocatière on top 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.
In the upper part of Canada’s range: 20% of its 2,611 towns expect more damage than Saint-Jérôme.
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 Saint-Jérôme’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).
10% of homes tested around Saint-Jérôme are over the radon guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · Area-wide: radon tests, counted over the Laurentides health region
More homes than usual test high around Saint-Jérôme: 10% against 6.6% for the typical Canadian town.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Radon runs higher around Saint-Jérôme than in most towns in Quebec: 10% over the guideline (8.2% is typical), 1.3% over 600.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
The 10–20% band holds 22% of Canada’s 2,611 towns, Saint-Jérôme among them; 4.6% rank above.
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 share describes the area, not a house: in Saint-Jérôme as anywhere, test to be sure.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Saint-Jérôme
Alerts for Saint-Jérôme 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. |
Alert Ready carries evacuation orders for Saint-Jérôme to phones; CWFIS shows the day’s fire danger.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Saint-Jérôme’s neighbours compare on hazards
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Saint-Jérôme | Low | $0.15 | 10% | Yes |
| Sainte-Sophie 19,467 · 7.2 km | Low | $0.12 | 10% | None listed |
| Saint-Colomban 19,080 · 8.3 km | Low | $0.11 | 10% | Yes |
| Prévost 14,275 · 8.5 km | Low | $0.088 | 10% | Yes |
| Sainte-Anne-des-Lacs 4,080 · 11 km | Low | $0.10 | 10% | None listed |
| Saint-Hippolyte 12,550 · 13 km | Low | $0.085 | 10% | None listed |
| Mirabel 68,471 · 14 km | Low | $0.16 | 10% | Yes |
Sainte-Sophie burns a little more than Saint-Jérôme, in the same low band (low here).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Saint-Jérôme faces
What to do about the hazards Saint-Jérôme 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
- Earthquakes are modelled. NRCan models what earthquakes would cost buildings each year on average, subdivision by subdivision; Saint-Jérôme’s figure is its subdivision’s.
- Flood studies aren’t flood zones. A study’s area can be a whole watershed or province, so being on the inventory says a map exists, not that a home in Saint-Jérôme floods.
- Radon is a survey. The radon share comes from about 14,000 long-term home tests in 2009–2011, pooled for now by the 2007 health region Saint-Jérôme sits in.
- Wildfire counts one way. Wildfire is read from the national burned-area record around Saint-Jérôme’s homes since 1986, a history of fire that may lower Risk but never raises it.
Questions about flooding and hazards in Saint-Jérôme
How is Saint-Jérôme’s Hazard risk Grade worked out?
Saint-Jérôme grades C− for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Is Saint-Jérôme at risk of wildfire?
Fire has reached 0.1% of the land around Saint-Jérôme since 1986 (last in 2025); at low, it neither helps nor hurts the grade.
How big is the earthquake risk in Saint-Jérôme?
NRCan’s model expects shaking to cost buildings in Saint-Jérôme $0.15 a year for every $1,000 of their value, on average over many years.
Is radon a problem in Saint-Jérôme?
Around Saint-Jérôme, 78 survey homes were tested and 10% came in over 200 Bq/m³, a guide to the area, not to any one home.
Does Saint-Jérôme flood?
Saint-Jérôme’s area has been studied for flooding, and the owner’s map shows which streets lie in a zone; the grade leaves flood out.
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).