Photo: Laroutedesvins · CC BY-SA 4.0Wildfire low, radon 8.2%: how Dunham stands on hazards
Wildfire isn’t Dunham’s worry: 0% of the land within 25 km burned since 1986 (0.000% a year). Seismic risk runs high: $0.072 of expected damage per $1,000 of buildings a year, the typical town $0.030. Hazard risk gives Dunham a grade of C+, from earthquakes and radon alone.
What stands out about Dunham’s hazards
Four national sources, each read for Dunham: earthquakes, radon, past fires and flood studies.
What Dunham faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Dunham grades C+ for hazard risk
Seismic risk and radon set Dunham’s grade, wildfire can drag it down, and flood mapping stays out of it.
Its place: #120 of 507 in Quebec and #1,865 of 2,589 Canadian towns.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. Small fires and grass fires are largely missing from the national burned-area record.
Few fires near Dunham: 0% within 5 km, 0% within 25 km
Past fire around Dunham’s homes, from the national burned-area record, with the fuel within 5 km.
A burn rate of 0.000% a year keeps Dunham in the low band (the typical Canadian town: 0.000%).
No fire has burned within 5 km of Dunham’s homes since 1986; the nearest burn is 11 km away.
Forest fuel is spread evenly around Dunham: 13% within 5 km, 10% 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
Near-zero burning puts Dunham with 144 of the 513 towns in Quebec, far below Mistissini 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.
Like most of Canada’s 2,610 towns (92%), Dunham is in the low band, with a burn rate of zero to three decimals; 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.
No flood study is listed for Dunham
What Canada’s Flood Map Inventory lists for Dunham: who studied flooding and where to see their maps.
Nationally, Dunham has no listed flood study; the municipality is the place to ask.
Towns with a flood study on file
Dunham has no flood study on file; only 45% of towns in Quebec do, against 58% across Canada.
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 Dunham’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 Dunham: $0.072 per $1,000 of buildings a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Dunham’s $0.072 is about 2.4 times the typical town’s $0.030: it sits in one of Canada’s more active seismic zones.
Shaking damage a year per $1,000 of building value
Dunham’s $0.072 sits under the median in Quebec, $0.14, and well under La Pocatière’s $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.
28% of Canada’s 2,611 towns expect more shaking damage than Dunham, which places it in the upper third.
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 Dunham’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).
Radon about average around Dunham: 8.2% over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · Area-wide: radon tests, counted over the Monteregie health region
The survey area of Dunham reads 8.2%, a shade from the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Dunham’s area, at 8.2%, is close to the median in Quebec (8.2%).
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Between 5% and 10% of tests over the guideline: Dunham, and 37% of Canada’s 2,611 towns; 26% are 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.
One home in Dunham can be high while next door is low; a three-month test settles it.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Dunham
Environment and Climate Change Canada issues the weather alerts for Dunham; 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. |
In fire season, check CWFIS for danger and active fires around Dunham, and listen to local authorities for orders.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Dunham’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 |
|---|---|---|---|---|
| Dunham | Low | $0.072 | 8.2% | None listed |
| Cowansville 17,269 · 6.7 km | Low | $0.089 | 8.2% | None listed |
| Brigham 2,386 · 11 km | Low | $0.099 | 8.2% | Yes |
| Frelighsburg 1,168 · 12 km | Low | $0.059 | 8.2% | None listed |
| Sutton 4,775 · 15 km | Low | $0.045 | 8.2% | None listed |
| Bedford 2,845 · 16 km | Low | $0.13 | 8.2% | None listed |
| Saint-Alphonse-de-Granby 3,545 · 19 km | Low | $0.10 | 8.2% | None listed |
The neighbour with the most fire is Cowansville (low), still no more than Dunham (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Dunham faces
Practical steps for Dunham’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.
- Clear needles and wood nearby.
- Keep a grab-and-go bag ready.
- In smoke, stay in; filter air.
- Has it had a radon test?
- Ask the municipality for flood maps.
- Are flood and wildfire insured?
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; Dunham’s figure is its subdivision’s.
- Radon is a survey. Health Canada’s survey tested some 14,000 homes over three months; until postal-area boundaries are loaded, Dunham takes its 2007 health region’s share.
- Wildfire counts one way. Wildfire is read from the national burned-area record around Dunham’s homes since 1986, a history of fire that may lower Risk but never raises it.
- Flood studies aren’t flood zones. The flood inventory points to maps; it is incomplete and not the official source, so ask the municipality about any street in Dunham.
Questions about flooding and hazards in Dunham
Does Dunham flood?
No study on Canada’s Flood Map Inventory covers Dunham (0), which doesn’t mean it has never been mapped, so ask the municipality.
Is Dunham at risk of wildfire?
Not much by Canadian standards: Dunham’s band is low, with 0% of the land within 25 km burned since 1986 (last in 2025), so wildfire doesn’t change its grade.
How is Dunham’s Hazard risk Grade worked out?
Hazard risk gives Dunham C+, weighing earthquakes and radon and counting wildfire only against it.
Is radon a problem in Dunham?
8.2% of the 110 homes Health Canada tested around Dunham topped the guideline; your own house needs its own test.
How big is the earthquake risk in Dunham?
In NRCan’s seismic model, Dunham’s buildings lose $0.072 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).