Photo: P199 · CC BY-SA 3.0Perth faces more hazards than 91% of Canadian towns
Wildfire isn’t Perth’s worry: 0% of the land within 25 km burned since 1986 (0.000% a year). Shaking is a bigger worry than in most places, at $0.081 a year per $1,000 of building value ($0.030 typical). More homes than usual carry radon here, 19% over the guideline where the typical town has 6.6%. Perth grades D for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Perth’s hazards
For Perth, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Perth faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Perth grades D for hazard risk
The grade weighs Perth’s seismic risk and radon equally, and wildfire is one-sided: a high band counts against a town, a low one earns nothing.
Its place: #854 of 866 in Ontario and #2,482 of 2,589 Canadian towns.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Little of the land around Perth has burned: 0% within 5 km, 0% within 25 km since 1986
Fires mapped since 1986 around where Perth’s residents live, and the fuel next to their homes.
In a typical year 0.000% of the land near Perth burns; the typical Canadian town sees 0.000%, and both are low.
Near or far, forest fuel covers a similar share around Perth: 6.3% within 5 km and 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 Ontario · highest of 871
Among the 871 towns in Ontario, Sioux Lookout burns fastest (0.16% a year); Perth is with the 638 near zero.
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.
92% of Canada’s 2,610 towns are in the low band and 7.5% above it; Perth is among the many where the yearly burn rate rounds to zero.
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 Perth is mapped in 2 studies, the newest by Rideau Valley Conservation Authority
Flood studies whose area touches Perth, from NRCan’s inventory, each linked to its owner.
2 studies on the inventory touch Perth, the newest Rideau Valley Conservation Authority’s from 2013, and their areas can be large, so they say maps exist, not that the town floods.
| Study | By | Year | Status |
|---|---|---|---|
| Tay River From Glen Tay Road to Lower Rideau Lake | Rideau Valley Conservation Authority | 2013 | final |
| Blueberry Creek | Rideau Valley Conservation Authority | 2010 | final |
Towns with a flood study on file
Its flood study puts Perth with 69% of towns in Ontario; Canada’s share is 58%.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood studies don’t enter the grade; they are listed so you can open the official map for Perth.
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.
Shaking is Perth’s costliest hazard: $0.081 a year per $1,000
NRCan’s seismic risk model: the damage shaking is expected to do to buildings each year, on average over many years.
At $0.081 per $1,000, Perth carries roughly 2.7 times the typical Canadian town’s earthquake risk ($0.030).
Shaking damage a year per $1,000 of building value
Perth’s $0.081 tops the median in Ontario, $0.043, though Alexandria reaches $0.21.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
More earthquake risk than most: only 28% of Canada’s 2,611 towns are above Perth.
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).
Only shaking damage to buildings in Perth is counted; landslides, liquefaction, tsunami and fire after a quake aren’t.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Radon runs high around Perth: 19% of tested homes over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline. · Measured across the Leeds, Grenville and Lanark District Health Unit: radon tests
Perth’s area, at 19%, is above the 6.6% of the typical Canadian town, so testing is worth more here than most places.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Perth, 19% of tests were over 200 Bq/m³ and 1.9% over 600, against a median of 4% in Ontario.
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, Perth 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.
Radon varies from house to house in Perth, 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 Perth
Alerts for Perth 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 Perth to phones; CWFIS shows the day’s fire danger.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Perth
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Perth | Low | $0.081 | 19% | Yes |
| Drummond/North Elmsley 8,817 · 7.0 km | Low | $0.088 | 19% | Yes |
| Tay Valley 6,171 · 10 km | Low | $0.064 | 19% | Yes |
| Smiths Falls 11,093 · 19 km | Low | $0.092 | 19% | Yes |
Drummond/North Elmsley burns a little more than Perth, 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 Perth faces
What to do about the hazards Perth 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.
- Clear needles and wood nearby.
- Keep a grab-and-go bag ready.
- In smoke, stay in; filter air.
- Has it had a radon test?
- Check the address on the flood map.
- Are flood and wildfire insured?
What this data can and can’t tell you
- Flood studies aren’t flood zones. NRCan’s inventory says where flood mapping exists, not where water goes; the map’s owner is the authority for Perth.
- Earthquakes are modelled. The earthquake figure is an expected loss, not a forecast, worked out by NRCan for each census subdivision, Perth’s included.
- Wildfire counts one way. Burned land within 25 km of where people live, averaged over 1986–2025 and checked for fuel near homes, is the measure; it looks back, not ahead, and only ever counts against Perth.
- Radon is a survey. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Perth is its health region’s, the survey’s design unit.
Questions about flooding and hazards in Perth
Is radon a problem in Perth?
In Health Canada’s survey, 19% of 108 homes tested in Perth’s area were above 200 Bq/m³, though only a test tells you about one house.
How is Perth’s Hazard risk Grade worked out?
Perth grades D for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Is Perth at risk of wildfire?
No meaningful wildfire history near Perth: 0% of nearby land since 1986, band low.
How big is the earthquake risk in Perth?
Expected earthquake damage in Perth comes to $0.081 a year for each $1,000 that buildings are worth.
Does Perth flood?
There is flood mapping for Perth on the national inventory, each study linked to its owner’s map, none of them graded.
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).