Photo: Veillg1 · CC BY-SA 4.0Flood mapping exists for Richelieu: 2 on record, latest by Gouvernement du Québec
Little of the land around Richelieu has burned: 0.1% within 25 km since 1986, or 0.002% a year. Earthquakes add more: NRCan’s model puts building losses at $0.18 a year per $1,000 of value, against $0.030 for the typical town. In Health Canada’s survey, 8.2% of homes tested in Richelieu’s area exceeded 200 Bq/m³, close to the typical 6.6%. Richelieu grades C− for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Richelieu’s hazards
For Richelieu, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Richelieu faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Richelieu: C−
For Richelieu, Risk will be the average of earthquakes and radon, with wildfire added only if it makes the average worse.
Its place: #337 of 507 in Quebec and #2,301 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Wildfire is rare near Richelieu: 0.1% of the land within 25 km burned since 1986, 0% within 5 km
Fires mapped since 1986 around where Richelieu’s residents live, and the fuel next to their homes.
Fire claims 0.002% of the land around Richelieu each year, a low band, with the typical Canadian town at 0.000%.
Since 1986 the nearest fire to Richelieu’s homes came within 8.4 km, never inside 5 km.
With 0.3% forest fuel within 5 km and 0.5% within 25 km, the land around Richelieu gives a fire little to burn.
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; Richelieu, 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, Richelieu 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.
Flooding around Richelieu is mapped in 2 studies, the newest by Gouvernement du Québec
Flood studies whose area touches Richelieu, from NRCan’s inventory, each linked to its owner.
2 studies on the inventory touch Richelieu, the newest Gouvernement du Québec’s from 2004, and their areas can be large, so they say maps exist, not that the town floods.
| Study | By | Year | Status |
|---|---|---|---|
| Brome-Missisquoi-Haut-Richelieu-Vallée-du-Richelieu-Rouville | Gouvernement du Québec | 2004 | final |
| Sorel-Chambly | Gouvernement du Québec | 1979 | final |
Towns with a flood study on file
Its flood study sets Richelieu apart in Quebec, where 45% of towns have one (Canada: 58%).
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
No single decade dominates: 2 studies for Richelieu between the 1970s and the 2000s.
Study dates as the NRCan inventory lists them, one count per study touching Richelieu.
Flood studies don’t enter the grade; they are listed so you can open the official map for Richelieu.
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 Richelieu $0.18 per $1,000 a year
NRCan’s seismic risk model: the damage shaking is expected to do to buildings each year, on average over many years.
Roughly 6 times the typical $0.030: Richelieu’s $0.18 marks real seismic exposure.
Shaking damage a year per $1,000 of building value
Richelieu’s $0.18 tops the median in Quebec, $0.14, though La Pocatière reaches $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: 13% of its 2,611 towns expect more damage than Richelieu.
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).
What a quake does after the shaking, fire, landslides, tsunami, falls outside NRCan’s figure for Richelieu.
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 Richelieu are over the radon guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
Around Richelieu, 8.2% of tested homes topped the guideline, near the typical Canadian town’s 6.6%. Figures for radon tests are published for the Monteregie health region as a whole, not for Richelieu alone.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Richelieu, 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.
Radon tops the guideline in a modest share of homes around Richelieu, a band holding 37% of Canada’s 2,611 towns; 26% 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.
Radon varies from house to house in Richelieu, so the survey is a reason to test, not a result for yours.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Richelieu
Alerts for Richelieu 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. |
Fire danger and active fires near Richelieu are mapped daily by the Canadian Wildland Fire Information System; evacuation orders come from the municipality or province.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Richelieu’s neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Richelieu | Low | $0.18 | 8.2% | Yes |
| Chambly 31,870 · 4.3 km | Low | $0.19 | 8.2% | Yes |
| Saint-Mathias-sur-Richelieu 4,598 · 4.8 km | Low | $0.18 | 8.2% | Yes |
| Marieville 11,910 · 5.9 km | Low | $0.16 | 8.2% | None listed |
| Carignan 12,618 · 6.8 km | Low | $0.18 | 8.2% | Yes |
| Saint-Basile-le-Grand 17,146 · 10 km | Low | $0.18 | 8.2% | Yes |
| Bienville 7,888 · 11 km | Low | $0.23 | 8.2% | None listed |
Nowhere around Richelieu burns more: Chambly, 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 Richelieu faces
Practical steps for Richelieu’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. Seismic risk is NRCan’s model of yearly building losses from shaking, averaged over many years and given for Richelieu’s census subdivision (a neighbourhood shows its city’s).
- Flood studies aren’t flood zones. Flood studies cover areas of every size, which is why the page lists them for Richelieu without grading them.
- 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 Richelieu until then.
- Wildfire counts one way. For Richelieu, wildfire means how much nearby land burned in the past forty years, a one-way input that can pull Risk down and nothing more.
Questions about flooding and hazards in Richelieu
How is Richelieu’s Hazard risk Grade worked out?
Hazard risk gives Richelieu C−, weighing earthquakes and radon and counting wildfire only against it.
Is radon a problem in Richelieu?
The area’s survey found 8.2% of 110 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Richelieu.
Is Richelieu at risk of wildfire?
Some, but Richelieu’s low band (0.1% of nearby land burned since 1986, latest 2025) is short of the level that counts.
Does Richelieu flood?
A flood study covers Richelieu on Canada’s Flood Map Inventory; open the owner’s map to check a street, since flood isn’t graded.
How big is the earthquake risk in Richelieu?
About $0.18 a year per $1,000 of building value, NRCan’s long-run expectation for Richelieu.
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).