Photo: Matt Biddulph from UK · CC BY-SA 2.0Hazards in Longueuil: wildfire low, radon over the guideline in 8.2% of tested homes
Little of the land around Longueuil has burned: 0.1% within 25 km since 1986, or 0.002% a year. Earthquakes add more: NRCan’s model puts building losses at $0.23 a year per $1,000 of value, against $0.030 for the typical town.
What stands out about Longueuil’s hazards
Four national sources, each read for Longueuil: earthquakes, radon, past fires and flood studies.
What Longueuil faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Longueuil: the grade is still to come
The grade weighs Longueuil’s seismic risk and radon equally, and wildfire is one-sided: a high band counts against a town, a low one earns nothing.
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.
Few fires near Longueuil: 0.1% within 5 km, 0.1% within 25 km
Past fire around Longueuil’s homes, from the national burned-area record, with the fuel within 5 km.
A burn rate of 0.002% a year keeps Longueuil in the low band (the typical Canadian town: 0.000%).
Little near Longueuil’s homes can carry a forest fire; only 0.3% of the land within 5 km is forest fuel, and 0.8% 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
Longueuil ranks 35th of the 514 towns in Quebec for burn rate, at 0.002% a year; Mistissini leads with 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, Longueuil 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.
The flood map inventory lists nothing for Longueuil
What Canada’s Flood Map Inventory lists for Longueuil: who studied flooding and where to see their maps.
Canada’s Flood Map Inventory lists no study whose area touches Longueuil, which doesn’t mean it has never been mapped.
Towns with a flood study on file
No study touches Longueuil; in Quebec, 45% of towns have one, below Canada’s 58%.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood is shown here, never graded: a study says where a map exists, not how many of Longueuil’s homes stand in a flood zone.
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.”
High seismic risk in Longueuil: $0.23 per $1,000 of buildings a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
At $0.23 per $1,000, Longueuil carries roughly 7.6 times the typical Canadian town’s earthquake risk ($0.030).
Shaking damage a year per $1,000 of building value
At $0.23, Longueuil 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 6.4% of Canada’s 2,611 towns expect more shaking damage than Longueuil.
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 model counts damage to Longueuil’s buildings and their occupants from shaking only: not liquefaction, landslides, tsunami or fires after a quake.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
8.2% of homes tested around Longueuil are over the radon guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline.
Longueuil’s area, at 8.2%, is close to the 6.6% of the typical Canadian town. Longueuil shares its radon tests numbers with the rest of the Monteregie health region.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Radon around Longueuil is ordinary for towns in Quebec: 8.2%, beside a median of 8.2%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
A middling share of high tests puts Longueuil with 37% of Canada’s 2,611 towns, below 26% of them.
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.
A survey sample isn’t a map: any home in Longueuil can be high, and a three-month test is the only way to know.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Longueuil
Environment and Climate Change Canada issues the weather alerts for Longueuil; Alert Ready carries the urgent ones to phones, radio and TV.
| 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. |
Smoke and fire warnings for Longueuil come through Environment Canada and Alert Ready; the fire map is CWFIS’s.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Longueuil
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Longueuil | Low | $0.23 | 8.2% | None listed |
| Saint-Robert 9,186 · 0.4 km | Low | $0.23 | 8.2% | None listed |
| Roberval 2,536 · 1.2 km | Low | $0.23 | 8.2% | None listed |
| Sacré-Coeur 20,375 · 1.6 km | Low | $0.23 | 8.2% | None listed |
| Saint-Jean-Vianney 13,181 · 1.7 km | Low | $0.23 | 8.2% | None listed |
| Saint-Vincent-de-Paul 8,352 · 1.8 km | Low | $0.23 | 8.2% | None listed |
| Laflèche 19,706 · 2.0 km | Low | $0.23 | 8.2% | None listed |
Nowhere around Longueuil burns more: Saint-Robert, the closest rival, is low to its low.
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Longueuil faces
What to do about the hazards Longueuil 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?
- Ask the municipality for flood maps.
- 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; Longueuil’s figure is its subdivision’s.
- 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 Longueuil sits in.
- 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 Longueuil floods.
- Wildfire counts one way. Wildfire is read from the national burned-area record around Longueuil’s homes since 1986, a history of fire that may lower Risk but never raises it.
Questions about flooding and hazards in Longueuil
Is Longueuil at risk of wildfire?
Less than most of Canada: 0.1% of the land within 25 km of Longueuil has burned since 1986, the last in 2024, a low band that leaves Risk alone.
Is radon a problem in Longueuil?
In Health Canada’s survey, 8.2% of 110 homes tested in Longueuil’s area were above 200 Bq/m³, though only a test tells you about one house.
Does Longueuil flood?
Nothing is listed for Longueuil on the national inventory (0); local maps may still exist with the municipality.
How is Longueuil’s Hazard risk Grade worked out?
Longueuil isn’t graded yet: Canada’s single grading run will set its Risk from earthquakes, radon and, one way only, wildfire.
How big is the earthquake risk in Longueuil?
In NRCan’s seismic model, Longueuil’s buildings lose $0.23 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).