Photo: Dillan Payne · CC BY-SA 4.0A quiet place for hazards: low wildfire, little earthquake risk, and 2.7% of tested homes over the radon guideline in Yonge-St.Clair’s area
No wildfire is mapped within 25 km of Yonge-St.Clair’s homes since 1986 (0% of the land, 0.000% a year). For earthquakes Yonge-St.Clair is middling, $0.043 a year per $1,000 against $0.030 for the typical town. Hazard risk gives Yonge-St.Clair a grade of A−, from earthquakes and radon alone.
What stands out about Yonge-St.Clair’s hazards
Four national sources, each read for Yonge-St.Clair: earthquakes, radon, past fires and flood studies.
What Yonge-St.Clair faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Yonge-St.Clair grades A− for hazard risk
For Yonge-St.Clair, Risk will be the average of earthquakes and radon, with wildfire added only if it makes the average worse.
Its place: #285 of 866 in Ontario and #700 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. The radon share rests on 74 home tests in the survey area, so a few homes move it. Small fires and grass fires are largely missing from the national burned-area record.
Little of the land around Yonge-St.Clair has burned: 0% within 5 km, 0% within 25 km since 1986
Past fire around Yonge-St.Clair’s homes, from the national burned-area record, with the fuel within 5 km.
Forty years of fire maps put Yonge-St.Clair at 0.000% a year, low next to the typical Canadian town’s 0.000%.
Only 1% of the land within 25 km of Yonge-St.Clair is forest fuel, and 0.1% close in.
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
Fire has taken almost none of the land around Yonge-St.Clair, as for 638 of the 871 towns in Ontario; Sioux Lookout tops the list at 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 Yonge-St.Clair 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 Yonge-St.Clair
What Canada’s Flood Map Inventory lists for Yonge-St.Clair: who studied flooding and where to see their maps.
No flood study on the national inventory covers Yonge-St.Clair; ask the municipality, which is the authority for its flood maps.
Towns with a flood study on file
Mapping in Ontario reaches 69% of towns, beside 58% across Canada, but not Yonge-St.Clair.
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 Yonge-St.Clair.
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.”
Expected shaking damage in Yonge-St.Clair: $0.043 a year per $1,000
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Nothing unusual about Yonge-St.Clair’s ground: $0.043 against a typical $0.030, 1.4 times.
Nobody publishes earthquake risk for Yonge-St.Clair alone, so this card uses the figure for the city of Toronto.
Shaking damage a year per $1,000 of building value
The median in Ontario is $0.043; Yonge-St.Clair, at $0.043, is right beside it, and Alexandria tops the list at $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.
Neither high nor low for Canada: 36% of the 2,611 towns expect more damage than Yonge-St.Clair.
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 Yonge-St.Clair’s 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).
Little radon around Yonge-St.Clair: 2.7% of area homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · Radon tests for the City of Toronto Health Unit
Yonge-St.Clair’s area, at 2.7%, is below the 6.6% of the typical Canadian town, though any one home can still be high.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
The median in Ontario is 4% over 200 Bq/m³; around Yonge-St.Clair it is 2.7%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
63% of Canada’s 2,611 towns have a higher share of homes over 200 Bq/m³ than Yonge-St.Clair’s band, which holds 37%.
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 Yonge-St.Clair 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 Yonge-St.Clair
Environment and Climate Change Canada issues the weather alerts for Yonge-St.Clair; 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. |
Smoke and fire warnings for Yonge-St.Clair come through Environment Canada and Alert Ready; the fire map is CWFIS’s.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Yonge-St.Clair
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Yonge-St.Clair | Low | $0.043 | 2.7% | None listed |
| Casa Loma 11,369 · 0.9 km | Low | $0.043 | 2.7% | None listed |
| Forest Hill South 11,059 · 1.4 km | Low | $0.043 | 2.7% | None listed |
| South Eglinton-Davisville 23,380 · 1.5 km | Low | $0.043 | 2.7% | None listed |
| Yonge-Eglinton 12,424 · 1.7 km | Low | $0.043 | 2.7% | Yes |
| Rosedale-Moore Park 20,268 · 1.7 km | Low | $0.043 | 2.7% | Yes |
| Annex 30,705 · 2.1 km | Low | $0.043 | 2.7% | Yes |
Fire is no heavier anywhere nearby than around Yonge-St.Clair (low), with Casa Loma next at low.
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Yonge-St.Clair faces
Practical steps for Yonge-St.Clair’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
- Wildfire counts one way. Wildfire is read from the national burned-area record around Yonge-St.Clair’s homes since 1986, a history of fire that may lower Risk but never raises it.
- 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 Yonge-St.Clair until then.
- Earthquakes are modelled. NRCan models what earthquakes would cost buildings each year on average, subdivision by subdivision; Yonge-St.Clair’s figure is its subdivision’s.
- Flood studies aren’t flood zones. Flood studies cover areas of every size, which is why the page lists them for Yonge-St.Clair without grading them.
Questions about flooding and hazards in Yonge-St.Clair
How big is the earthquake risk in Yonge-St.Clair?
NRCan’s model expects shaking to cost buildings in Yonge-St.Clair $0.043 a year for every $1,000 of their value, on average over many years.
How is Yonge-St.Clair’s Hazard risk Grade worked out?
Hazard risk gives Yonge-St.Clair A−, weighing earthquakes and radon and counting wildfire only against it.
Does Yonge-St.Clair flood?
No study on Canada’s Flood Map Inventory covers Yonge-St.Clair (0), which doesn’t mean it has never been mapped, so ask the municipality.
Is radon a problem in Yonge-St.Clair?
2.7% of the 74 homes Health Canada tested around Yonge-St.Clair topped the guideline; your own house needs its own test.
Is Yonge-St.Clair at risk of wildfire?
Very little by the national record: Yonge-St.Clair’s band is low, with 0% of the land within 25 km burned since 1986, so wildfire doesn’t change its grade.
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).