Photo: Andrepoiy · CC BY-SA 4.0Upper Thornhill Estates faces fewer hazards than 90% of Canadian towns
Wildfire isn’t Upper Thornhill Estates’ worry: 0% of the land within 25 km burned since 1986 (0.000% a year). Earthquake risk in Upper Thornhill Estates is ordinary: NRCan’s model puts building losses at $0.028 a year per $1,000 of value, close to the typical town’s $0.030. In Health Canada’s survey, just 0% of homes tested in the area exceeded 200 Bq/m³ (6.6% typical). Upper Thornhill Estates grades A for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Upper Thornhill Estates’s hazards
Four national sources, each read for Upper Thornhill Estates: earthquakes, radon, past fires and flood studies.
What Upper Thornhill Estates faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Upper Thornhill Estates grades A for hazard risk
Two inputs always count for Upper Thornhill Estates, earthquakes and radon; the third, wildfire, counts only against a town.
Its place: #74 of 866 in Ontario and #383 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 Upper Thornhill Estates has burned: 0% within 5 km, 0% within 25 km since 1986
Fires mapped since 1986 around where Upper Thornhill Estates’ residents live, and the fuel next to their homes.
Low: the land around Upper Thornhill Estates burns at 0.000% a year, where the typical Canadian town sees 0.000%.
Forest makes up 2.1% of the land within 5 km of Upper Thornhill Estates and 4.8% 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 Ontario · highest of 871
Near-zero burning puts Upper Thornhill Estates with 638 of the 871 towns in Ontario, far below Sioux Lookout 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.
Only 7.5% of Canada’s 2,610 towns are above the low band, which holds 92%; Upper Thornhill Estates, at a rounded zero, is far from them.
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.
A flood study covers Upper Thornhill Estates, from Toronto Regional Conservation Authority: 1 on the inventory
Flood studies whose area touches Upper Thornhill Estates, from NRCan’s inventory, each linked to its owner.
Toronto Regional Conservation Authority studied flooding in an area that includes Upper Thornhill Estates (2021); open its map to see which streets lie in a flood zone.
| Study | By | Year | Status |
|---|---|---|---|
| Toronto Floodline Consolidation | Toronto Regional Conservation Authority | 2021 | final |
Towns with a flood study on file
Its flood study puts Upper Thornhill Estates 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 Upper Thornhill Estates.
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.
Expected shaking damage in Upper Thornhill Estates: $0.028 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 $0.028 per $1,000, Upper Thornhill Estates’ earthquake risk is about the typical Canadian town’s ($0.030; 0.9 times).
For earthquake risk, the only official count covers all of the city of Vaughan, Upper Thornhill Estates included.
Shaking damage a year per $1,000 of building value
Earthquake risk in Ontario peaks in Alexandria ($0.21); Upper Thornhill Estates, at $0.028, is below the median of $0.043.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Middle of the pack: 51% of Canada’s 2,611 towns have more earthquake risk than Upper Thornhill Estates.
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 Upper Thornhill Estates’ 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).
Little radon around Upper Thornhill Estates: 0% of area homes over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
Upper Thornhill Estates’ survey area reads 0% over the guideline, under the typical Canadian town’s 6.6%. Figures for radon tests are published for the York Regional Health Unit as a whole, not for Upper Thornhill Estates alone.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Upper Thornhill Estates’ area, at 0%, is below the median in Ontario (4%).
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
The quietest radon band, under 5%, holds 37% of Canada’s 2,611 towns and Upper Thornhill Estates; 63% sit higher.
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 Upper Thornhill Estates 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 Upper Thornhill Estates
Alerts for Upper Thornhill Estates 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. |
Fire danger and active fires near Upper Thornhill Estates are mapped daily by the Canadian Wildland Fire Information System; evacuation orders come from the municipality or province.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Upper Thornhill Estates’ neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Upper Thornhill Estates | Low | $0.028 | 0% | Yes |
| The Valleys of Thornhill 9,979 · 2.1 km | Low | $0.028 | 0% | Yes |
| Hope 6,997 · 2.9 km | Low | $0.028 | 0% | Yes |
| Carrville Corners 13,004 · 2.9 km | Low | $0.028 | 0% | Yes |
| Richmond Hill 222,031 · 3.5 km | Low | $0.028 | 0% | Yes |
| Thornhill Woods 13,237 · 4.0 km | Low | $0.028 | 0% | Yes |
| Dufferin Hill 7,910 · 4.1 km | Low | $0.028 | 0% | Yes |
The fire record around Richmond Hill is a touch heavier than Upper Thornhill Estates’, but the band is the same: low (here low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Upper Thornhill Estates faces
What to do about the hazards Upper Thornhill Estates 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
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Upper Thornhill Estates’ 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. 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 Upper Thornhill Estates floods.
- 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 Upper Thornhill Estates’.
- 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 Upper Thornhill Estates sits in.
Questions about flooding and hazards in Upper Thornhill Estates
How big is the earthquake risk in Upper Thornhill Estates?
About $0.028 a year per $1,000 of building value, NRCan’s long-run expectation for Upper Thornhill Estates.
Is radon a problem in Upper Thornhill Estates?
In Health Canada’s survey, 0% of 95 homes tested in Upper Thornhill Estates’ area were above 200 Bq/m³, though only a test tells you about one house.
Does Upper Thornhill Estates flood?
Upper Thornhill Estates’ area has been studied for flooding, and the owner’s map shows which streets lie in a zone; the grade leaves flood out.
Is Upper Thornhill Estates at risk of wildfire?
The burned-area record shows next to nothing around Upper Thornhill Estates (0% within 25 km since 1986), so its band is low.
How is Upper Thornhill Estates’s Hazard risk Grade worked out?
Upper Thornhill Estates grades A for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the 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).