Photo: Ken Lund from Reno, Nevada, USA · CC BY-SA 2.0Perth South’s hazards at a glance: a low wildfire record and 12% of area homes over the radon guideline
The national fire record shows next to nothing around Perth South, 0% of the land within 25 km since 1986 (0.000% a year). Earthquake risk in Perth South is ordinary: NRCan’s model puts building losses at $0.017 a year per $1,000 of value, close to the typical town’s $0.030. Perth South grades B− for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Perth South’s hazards
Four national sources, each read for Perth South: earthquakes, radon, past fires and flood studies.
What Perth South faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Perth South: B−
Two inputs always count for Perth South, earthquakes and radon; the third, wildfire, counts only against a town.
Its place: #646 of 866 in Ontario and #1,578 of 2,589 Canadian towns.
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.
Little of the land around Perth South has burned: 0% within 5 km, 0% within 25 km since 1986
Fires mapped since 1986 around where Perth South’s residents live, and the fuel next to their homes.
In a typical year 0.000% of the land near Perth South burns; the typical Canadian town sees 0.000%, and both are low.
Little near Perth South’s homes can carry a forest fire; only 1.6% of the land within 5 km is forest fuel, and 0.6% 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
To three decimals the burn rate around Perth South is zero, as for 638 of the 871 towns in Ontario, while Sioux Lookout reaches 0.16%.
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.
The low band holds 92% of Canada’s 2,610 towns, and Perth South sits at its very bottom; only 7.5% are above it.
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 Perth South
Flood studies whose area touches Perth South, from NRCan’s inventory, each linked to its owner.
Nationally, Perth South has no listed flood study; the municipality is the place to ask.
Towns with a flood study on file
Mapping in Ontario reaches 69% of towns, beside 58% across Canada, but not Perth South.
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 Perth South.
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.”
Earthquakes cost buildings in Perth South $0.017 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.
With $0.017 of shaking damage a year per $1,000, Perth South is about even with the typical $0.030 (0.6 times).
Shaking damage a year per $1,000 of building value
Perth South’s $0.017 sits under the median in Ontario, $0.043, and well under Alexandria’s $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.
Perth South is in the lower part of Canada’s range for earthquake risk; 70% of the 2,611 towns are higher.
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 Perth South’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).
Test for radon in Perth South: 12% of area homes were over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
At 12% over the guideline, the area around Perth South beats the typical Canadian town’s 6.6%. For radon tests, the only official count covers all of the Perth District Health Unit, Perth South included.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Perth South, 12% of tests were over 200 Bq/m³ and 0.9% 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.
4.6% of Canada’s 2,611 towns have a higher share of homes over 200 Bq/m³ than Perth South, in the 10–20% band with 22%.
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 Perth South 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 Perth South
Environment and Climate Change Canada issues the weather alerts for Perth South; 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 Perth South, and listen to local authorities for orders.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Perth South
The same four hazards for the places next door.
Perth South’s low band tops its neighbours; St. Marys is next (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Perth South faces
What to do about the hazards Perth South 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?
- Ask the municipality for flood maps.
- Are flood and wildfire insured?
What this data can and can’t tell you
- 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 Perth South floods.
- 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 Perth South sits in.
- 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 Perth South’s.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Perth South’s 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 Perth South
Is radon a problem in Perth South?
Around Perth South, 108 survey homes were tested and 12% came in over 200 Bq/m³, a guide to the area, not to any one home.
Does Perth South flood?
With 0 studies on the inventory, Perth South’s flood risk is unmapped nationally; check with the municipality before buying.
How big is the earthquake risk in Perth South?
About $0.017 a year per $1,000 of building value, NRCan’s long-run expectation for Perth South.
Is Perth South at risk of wildfire?
The burned-area record shows next to nothing around Perth South (0% within 25 km since 1986), so its band is low.
How is Perth South’s Hazard risk Grade worked out?
Perth South’s Hazard risk grade is B−, built on earthquakes and radon with a one-sided wildfire input.
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).