Photo: ChadPerez49 · CC BY-SA 3.0Upper Cornell faces fewer hazards than 88% of Canadian towns
No wildfire is mapped within 25 km of Upper Cornell’s homes since 1986 (0% of the land, 0.001% a year). NRCan expects $0.034 of shaking damage a year per $1,000 of buildings in Upper Cornell, near the typical $0.030. Radon is lower than usual: 0% of tested homes in the survey area topped the guideline, against 6.6% for the typical town. Hazard risk gives Upper Cornell a grade of A; its wildfire band pulls it down.
What stands out about Upper Cornell’s hazards
Four national sources, each read for Upper Cornell: earthquakes, radon, past fires and flood studies.
What Upper Cornell faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Upper Cornell: A
Earthquake risk and radon make Upper Cornell’s grade; wildfire can only lower it, never raise it, and flood studies are listed but not scored.
Its place: #165 of 866 in Ontario and #484 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 Cornell has burned: 0% within 5 km, 0% within 25 km since 1986
Past fire around Upper Cornell’s homes, from the national burned-area record, with the fuel within 5 km.
Fire claims 0.001% of the land around Upper Cornell each year, a low band, with the typical Canadian town at 0.000%.
The 5 km ring around Upper Cornell’s homes is clear of burns since 1986, the nearest 7.3 km out.
The forest starts beyond town: 3.8% of the land within 5 km of Upper Cornell’s homes is forest fuel, against 8.9% 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
In the top quarter in Ontario: Upper Cornell ranks 83rd of 871 at 0.001% a year, with Sioux Lookout first 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 takes in 92% of Canada’s 2,610 towns, Upper Cornell among them, though its rate is above zero; 7.5% rank higher.
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.
Upper Cornell is on the flood map inventory: 2 studies, latest by Toronto Regional Conservation Authority
What Canada’s Flood Map Inventory lists for Upper Cornell: who studied flooding and where to see their maps.
The newest of 2 studies covering Upper Cornell is Toronto Regional Conservation Authority’s, from 2021; open its map to see the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Toronto Floodline Consolidation | Toronto Regional Conservation Authority | 2021 | final |
| Duffins Creek | Toronto and Region Conservation Authority | 2020 | final |
Towns with a flood study on file
Flood maps are common in Ontario: 69% of towns have one, against 58% nationally, and Upper Cornell is among them.
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 Cornell.
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.
Earthquakes cost buildings in Upper Cornell $0.034 per $1,000 a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Earthquake losses in Upper Cornell, $0.034 per $1,000, are in line with the typical $0.030 (1.1 times).
Upper Cornell shares its earthquake risk numbers with the rest of the city of Markham.
Shaking damage a year per $1,000 of building value
At $0.034, Upper Cornell is below the typical town in Ontario ($0.043); Alexandria is highest 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.
Upper Cornell’s earthquake risk lands near the centre of Canada’s range; 46% 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 loss is to Upper Cornell’s buildings alone, from ground shaking; infrastructure and secondary hazards are left out.
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 Cornell: 0% of area homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · The radon tests numbers here cover the York Regional Health Unit
Fewer homes than usual test high around Upper Cornell: 0% against 6.6% for the typical Canadian town.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Against the typical town in Ontario (4%), the area around Upper Cornell has fewer high tests: 0%.
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 Upper Cornell’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.
The share describes the area, not a house: in Upper Cornell as anywhere, test to be sure.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Upper Cornell
Alerts for Upper Cornell 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. |
Evacuation orders for Upper Cornell come from the municipality or the province, while CWFIS maps fire danger every day.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Upper Cornell’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 |
|---|---|---|---|---|
| Upper Cornell | Low | $0.034 | 0% | Yes |
| Cornell 22,014 · 1.2 km | Low | $0.034 | 0% | Yes |
| Greensborough 19,270 · 1.8 km | Low | $0.034 | 0% | Yes |
| Mount Joy 8,345 · 2.7 km | Low | $0.034 | 0% | Yes |
| Markham Village 10,319 · 2.8 km | Low | $0.034 | 0% | Yes |
| Wismer Commons 20,591 · 3.6 km | Low | $0.034 | 0% | Yes |
| Box Grove 25,496 · 5.0 km | Low | $0.034 | 0% | Yes |
Among its neighbours Upper Cornell has the most fire on record (low); Cornell follows (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Upper Cornell faces
Practical steps for Upper Cornell’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 Upper Cornell’s.
- 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 Cornell 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 Upper Cornell sits in.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Upper Cornell’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 Upper Cornell
How is Upper Cornell’s Hazard risk Grade worked out?
Upper Cornell grades A for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Is Upper Cornell at risk of wildfire?
Some, but Upper Cornell’s low band (0% of nearby land burned since 1986, latest 2001) is short of the level that counts.
How big is the earthquake risk in Upper Cornell?
NRCan’s model expects shaking to cost buildings in Upper Cornell $0.034 a year for every $1,000 of their value, on average over many years.
Is radon a problem in Upper Cornell?
The area’s survey found 0% of 95 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Upper Cornell.
Does Upper Cornell flood?
Upper Cornell’s area has been studied for flooding, and the owner’s map shows which streets lie in a zone; the grade leaves flood out.
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).