Photo: Silver Dovelet · CC BY-SA 3.0Mount Joy faces fewer hazards than 88% of Canadian towns
For Mount Joy, wildfire history is close to nil: 0% of nearby land since 1986, 0.001% a year. Seismic risk in Mount Joy sits near the middle: $0.034 of expected damage per $1,000 of buildings a year, the typical town $0.030. In Health Canada’s survey, just 0% of homes tested in the area exceeded 200 Bq/m³ (6.6% typical). Mount Joy grades A for hazard risk, with wildfire counted against it.
What stands out about Mount Joy’s hazards
For Mount Joy, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Mount Joy faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Mount Joy grades A for hazard risk
Two inputs always count for Mount Joy, earthquakes and radon; the third, wildfire, counts only against a town.
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. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Wildfire is rare near Mount Joy: 0% of the land within 25 km burned since 1986, 0% within 5 km
Past fire around Mount Joy’s homes, from the national burned-area record, with the fuel within 5 km.
A burn rate of 0.001% a year keeps Mount Joy in the low band (the typical Canadian town: 0.000%).
Fire has stayed at least 8.3 km from Mount Joy’s homes since 1986.
Close to Mount Joy there is little to burn (1.3% forest fuel within 5 km), but 8.2% of the land within 25 km is forest.
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
Mount Joy ranks 83rd of the 871 towns in Ontario for burn rate, at 0.001% a year; Sioux Lookout leads with 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.
Some fire is mapped around Mount Joy, but not enough to leave the low band, where 92% of Canada’s 2,610 towns are; 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.
A flood study covers Mount Joy, from Toronto Regional Conservation Authority: 1 on the inventory
What Canada’s Flood Map Inventory lists for Mount Joy: who studied flooding and where to see their maps.
Toronto Regional Conservation Authority holds the flood mapping that covers Mount Joy (2021), linked below.
| 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, Mount Joy 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 studies don’t enter the grade; they are listed so you can open the official map for Mount Joy.
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 Mount Joy $0.034 per $1,000 a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Mount Joy’s $0.034 is close to the typical town’s $0.030 (1.1 times as much).
Shaking damage a year per $1,000 of building value
Below the middle in Ontario: Mount Joy’s $0.034 against a median of $0.043; Alexandria has $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.
Middle of the pack: 46% of Canada’s 2,611 towns have more earthquake risk than Mount Joy.
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).
Only shaking damage to buildings in Mount Joy is counted; landslides, liquefaction, tsunami and fire after a quake aren’t.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean). · Area behind the earthquake risk figures: the city of Markham
Radon runs low around Mount Joy: 0% of tested homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · Area-wide: radon tests, counted over the York Regional Health Unit
At 0% over the guideline, the area around Mount Joy is under the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
The median in Ontario is 4% over 200 Bq/m³; around Mount Joy it is 0%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Mount Joy is in the lowest band, with 37% of Canada’s 2,611 towns: under 5% of tests over the guideline, while 63% have more.
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.
Whatever Mount Joy’s area share, the reading that matters is your own home’s, over a winter.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Mount Joy
Alerts for Mount Joy 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 Mount Joy 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 Mount Joy’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 |
|---|---|---|---|---|
| Mount Joy | Low | $0.034 | 0% | Yes |
| Markham Village 10,319 · 0.9 km | Low | $0.034 | 0% | Yes |
| Greensborough 19,270 · 1.2 km | Low | $0.034 | 0% | Yes |
| Wismer Commons 20,591 · 1.6 km | Low | $0.034 | 0% | Yes |
| Quantztown 13,146 · 2.4 km | Low | $0.034 | 0% | Yes |
| Upper Cornell 8,304 · 2.7 km | Low | $0.034 | 0% | Yes |
| Cornell 22,014 · 2.9 km | Low | $0.034 | 0% | Yes |
Fire is no heavier anywhere nearby than around Mount Joy (low), with Markham Village next at low.
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Mount Joy faces
What to do about the hazards Mount Joy 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. Burned land within 25 km of where people live, averaged over 1986–2025 and checked for fuel near homes, is the measure; it looks back, not ahead, and only ever counts against Mount Joy.
- Earthquakes are modelled. The earthquake figure is an expected loss, not a forecast, worked out by NRCan for each census subdivision, Mount Joy’s included.
- 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 Mount Joy 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 Mount Joy sits in.
Questions about flooding and hazards in Mount Joy
Is Mount Joy at risk of wildfire?
Less than most of Canada: 0% of the land within 25 km of Mount Joy has burned since 1986, the last in 2001, a low band that leaves Risk alone.
Is radon a problem in Mount Joy?
In Health Canada’s survey, 0% of 95 homes tested in Mount Joy’s area were above 200 Bq/m³, though only a test tells you about one house.
How is Mount Joy’s Hazard risk Grade worked out?
Mount Joy grades A for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Does Mount Joy flood?
Mount Joy’s area has been studied for flooding, and the owner’s map shows which streets lie in a zone; the grade leaves flood out.
How big is the earthquake risk in Mount Joy?
NRCan’s model expects shaking to cost buildings in Mount Joy $0.034 a year for every $1,000 of their value, on average over many years.
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).