Photo: Saud · CC BY-SA 4.0A flood study covers Thorncliffe Park: 1 on the national inventory, the newest from Toronto Regional Conservation Authority
No wildfire is mapped within 25 km of Thorncliffe Park’s homes since 1986 (0% of the land, 0.001% a year). Shaking is about as much of a worry in Thorncliffe Park as in most places, at $0.043 a year per $1,000 of building value ($0.030 typical). Radon is lower than usual: 2.7% of tested homes in the survey area topped the guideline, against 6.6% for the typical town. Hazard risk gives Thorncliffe Park a grade of A−; its wildfire band pulls it down.
What stands out about Thorncliffe Park’s hazards
Four national sources, each read for Thorncliffe Park: earthquakes, radon, past fires and flood studies.
What Thorncliffe Park faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Thorncliffe Park: A−
Earthquake risk and radon make Thorncliffe Park’s grade; wildfire can only lower it, never raise it, and flood studies are listed but not scored.
Its place: #285 of 866 in Ontario and #700 of 2,589 Canadian towns.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. Only 74 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.
Little of the land around Thorncliffe Park has burned: 0% within 5 km, 0% within 25 km since 1986
Past fire around Thorncliffe Park’s homes, from the national burned-area record, with the fuel within 5 km.
Low: the land around Thorncliffe Park burns at 0.001% a year, where the typical Canadian town sees 0.000%.
The 5 km ring around Thorncliffe Park’s homes is clear of burns since 1986, the nearest 23 km out.
Land that isn’t forest covers nearly all the ground around Thorncliffe Park: forest fuel is 0.3% within 5 km and 1.3% 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
At 0.001% a year, Thorncliffe Park is near the top in Ontario: 83rd of 871, behind Sioux Lookout (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.
Low, like 92% of the country’s 2,610 towns: the land around Thorncliffe Park burns, but slower than in the 7.5% 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.
Thorncliffe Park is on the flood map inventory: 1 study, by Toronto Regional Conservation Authority
What Canada’s Flood Map Inventory lists for Thorncliffe Park: who studied flooding and where to see their maps.
The flood study touching Thorncliffe Park is Toronto Regional Conservation Authority’s, dated 2021; its own map shows the zones street by street.
| Study | By | Year | Status |
|---|---|---|---|
| Toronto Floodline Consolidation | Toronto Regional Conservation Authority | 2021 | final |
Towns with a flood study on file
Mapping in Ontario reaches 69% of towns, Thorncliffe Park included, beside 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 Thorncliffe Park’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.”
Natural Resources Canada, Canada Flood Map Inventory; links go to each study’s owner.
Ordinary seismic risk in Thorncliffe Park: $0.043 per $1,000 of buildings a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Nothing unusual about Thorncliffe Park’s ground: $0.043 against a typical $0.030, 1.4 times.
Shaking damage a year per $1,000 of building value
The median in Ontario is $0.043; Thorncliffe Park, 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.
Around half of Canada’s 2,611 towns expect more shaking damage than Thorncliffe Park (36%).
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 Thorncliffe Park’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). · Earthquake risk published for the city of Toronto, not by town
Little radon around Thorncliffe Park: 2.7% of area homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline.
Thorncliffe Park’s survey area reads 2.7% over the guideline, under the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Against the typical town in Ontario (4%), the area around Thorncliffe Park has fewer high tests: 2.7%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Few tests over the guideline: Thorncliffe Park shares the bottom band with 37% of Canada’s 2,611 towns, below the other 63%.
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.
The share describes the area, not a house: in Thorncliffe Park as anywhere, test to be sure.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Data for radon tests covers the City of Toronto Health Unit
Weather and fire alerts for Thorncliffe Park
Environment and Climate Change Canada issues the weather alerts for Thorncliffe Park; 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 Thorncliffe Park come through Environment Canada and Alert Ready; the fire map is CWFIS’s.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Thorncliffe Park’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 |
|---|---|---|---|---|
| Thorncliffe Park | Low | $0.043 | 2.7% | Yes |
| Old East York 9,175 · 1.2 km | Low | $0.043 | 2.7% | Yes |
| Leaside-Bennington 16,710 · 1.7 km | Low | $0.043 | 2.7% | Yes |
| Broadview North 11,080 · 1.8 km | Low | $0.043 | 2.7% | Yes |
| Flemingdon Park 22,553 · 1.9 km | Low | $0.043 | 2.7% | Yes |
| Danforth East York 17,073 · 2.0 km | Low | $0.043 | 2.7% | Yes |
| Danforth 9,364 · 2.4 km | Low | $0.043 | 2.7% | None listed |
Among its neighbours Thorncliffe Park has the most fire on record (low); Old East York follows (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Thorncliffe Park faces
Practical steps for Thorncliffe Park’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?
- Check the address on the flood map.
- 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 Thorncliffe Park’s.
- Radon is a survey. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Thorncliffe Park is its health region’s, the survey’s design unit.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Thorncliffe Park’s homes burned each year from 1986 to 2025, past fire rather than a forecast, and it can only lower Risk.
- 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 Thorncliffe Park.
Questions about flooding and hazards in Thorncliffe Park
How big is the earthquake risk in Thorncliffe Park?
NRCan’s model expects shaking to cost buildings in Thorncliffe Park $0.043 a year for every $1,000 of their value, on average over many years.
Is Thorncliffe Park at risk of wildfire?
Some, but Thorncliffe Park’s low band (0% of nearby land burned since 1986, latest 2001) is short of the level that counts.
How is Thorncliffe Park’s Hazard risk Grade worked out?
Thorncliffe Park’s Hazard risk grade is A−, built on earthquakes and radon with a one-sided wildfire input.
Does Thorncliffe Park flood?
There is flood mapping for Thorncliffe Park on the national inventory, each study linked to its owner’s map, none of them graded.
Is radon a problem in Thorncliffe Park?
The area’s survey found 2.7% of 74 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Thorncliffe Park.
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).