Photo: The original uploader was Cherkowski at Wikipedia . · CC BY 2.5Radon is Cornwallis’ main hazard: 44% of tested homes in its area top Health Canada’s guideline
Some 2.8% of the land within 25 km of Cornwallis has burned since 1986; at 0.07% a year that is moderate, not high. Shaking is less of a worry than in most places, at $0.005 a year per $1,000 of building value ($0.030 typical). Hazard risk gives Cornwallis a grade of B−; its wildfire band pulls it down.
What stands out about Cornwallis’s hazards
Four national sources, each read for Cornwallis: earthquakes, radon, past fires and flood studies.
What Cornwallis faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Cornwallis grades B− for hazard risk
Seismic risk and radon set Cornwallis’ grade, wildfire can drag it down, and flood mapping stays out of it.
Its place: #170 of 185 in Manitoba and #1,713 of 2,589 Canadian towns.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. Only 79 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.
Some fire around Cornwallis: 2.8% of the land within 25 km since 1986, 0.6% within 5 km
Fires mapped since 1986 around where Cornwallis’ residents live, and the fuel next to their homes.
Moderate: the land around Cornwallis burns at 0.07% a year, where the typical Canadian town sees 0.000%.
Forest makes up 0% of the land within 5 km of Cornwallis and 0.4% within 25 km, little for a forest fire to run through.
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 Manitoba · highest of 189
Cornwallis ranks 17th of the 189 towns in Manitoba for burn rate, at 0.07% a year; Flin Flon (Part) leads with 1.68%.
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.
Moderate puts Cornwallis above most of Canada’s 2,610 towns, yet 2.1% rank high or very high and 5.4% share its band.
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.
Cornwallis is on the flood map inventory: 1 study, by Hydrologic Forecasting and Water Management Branch of Manitoba Transporation and Infrastructure
Flood studies whose area touches Cornwallis, from NRCan’s inventory, each linked to its owner.
A 2025 study by Hydrologic Forecasting and Water Management Branch of Manitoba Transporation and Infrastructure covers Cornwallis, and its map, not the inventory, shows the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Hydrodynamic Modelling Study for the Upper Assiniboine River: Mapped communities-St. Lazarre and Brandon | Hydrologic Forecasting and Water Management Branch of Manitoba Transporation and Infrastructure | 2025 | final · not public |
Towns with a flood study on file
Only 18% of towns in Manitoba have a flood study, short of Canada’s 58%; Cornwallis is one of them.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Nothing here counts toward Risk; the studies are pointers to the maps their owners keep for Cornwallis.
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 Cornwallis just $0.005 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.
Shaking costs the typical town $0.030 a year; in Cornwallis it is only $0.005, 0.2 times as much.
Shaking damage a year per $1,000 of building value
About level with the typical town in Manitoba: Cornwallis’ $0.005 against $0.006; Virden reaches $0.007.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Nearly every one of Canada’s 2,611 towns (96%) expects more shaking damage than Cornwallis.
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).
Roads, pipes and bridges aren’t in Cornwallis’ figure, nor landslides or tsunami: it is buildings and shaking.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Test for radon in Cornwallis: 44% of area homes were over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline. · Area-wide: radon tests, counted over the Brandon health region
More homes than usual test high around Cornwallis: 44% against 6.6% for the typical Canadian town.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
More homes top the guideline around Cornwallis (44%) than in the typical town in Manitoba (12%); 3.8% went over 600.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
At least three tests in ten top the guideline around Cornwallis, a level reached by 1.5% of Canada’s towns.
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 Cornwallis 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 Cornwallis
Environment and Climate Change Canada issues the weather alerts for Cornwallis; 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. |
For fires near Cornwallis, the national fire information system maps danger and active fires daily; local authorities give any evacuation order.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Cornwallis
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Cornwallis | Moderate | $0.005 | 44% | Yes |
| Brandon 59,444 · 18 km | Low | $0.005 | 44% | Yes |
Among its neighbours Cornwallis has the most fire on record (moderate); Brandon follows (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Cornwallis faces
Practical steps for Cornwallis’ hazards, most pressing first.
- Clear needles and wood nearby.
- Keep a grab-and-go bag ready.
- In smoke, stay in; filter air.
- 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.
- Has it had a radon test?
- Check the address on the flood map.
- How close is the forest edge?
- Are flood and wildfire insured?
What this data can and can’t tell you
- 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 Cornwallis’.
- Radon is a survey. Health Canada’s survey tested some 14,000 homes over three months; until postal-area boundaries are loaded, Cornwallis takes its 2007 health region’s share.
- 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 Cornwallis.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Cornwallis’ homes burned each year from 1986 to 2025, past fire rather than a forecast, and it can only lower Risk.
Questions about flooding and hazards in Cornwallis
How big is the earthquake risk in Cornwallis?
Expected earthquake damage in Cornwallis comes to $0.005 a year for each $1,000 that buildings are worth.
How is Cornwallis’s Hazard risk Grade worked out?
Cornwallis grades B− for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Does Cornwallis flood?
The inventory lists a study touching Cornwallis; whether a given street floods is on that map, not in the grade.
Is Cornwallis at risk of wildfire?
Some, but Cornwallis’ moderate band (2.8% of nearby land burned since 1986, latest 2023) is short of the level that counts.
Is radon a problem in Cornwallis?
The area’s survey found 44% of 79 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Cornwallis.
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).