Photo: Jfvoll · CC BY-SA 4.0Hazard risk in Wellesley is lower than in 88% of Canadian towns
The national fire record shows next to nothing around Wellesley, 0% of the land within 25 km since 1986 (0.000% a year). Shaking is about as much of a worry in Wellesley as in most places, at $0.016 a year per $1,000 of building value ($0.030 typical). Radon is lower than usual: 4% of tested homes in the survey area topped the guideline, against 6.6% for the typical town. Wellesley grades A for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Wellesley’s hazards
For Wellesley, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Wellesley faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Wellesley: A
For Wellesley, Risk will be the average of earthquakes and radon, with wildfire added only if it makes the average worse.
Its place: #188 of 866 in Ontario and #508 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.
Few fires near Wellesley: 0% within 5 km, 0% within 25 km
Fires mapped since 1986 around where Wellesley’s residents live, and the fuel next to their homes.
The land within 25 km of Wellesley burns at 0.000% a year on average, the low band; the typical Canadian town: 0.000%.
Forest makes up 1.3% of the land within 5 km of Wellesley and 1.5% 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
Among the 871 towns in Ontario, Sioux Lookout burns fastest (0.16% a year); Wellesley is with the 638 near zero.
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.
Measured against 2,610 towns, Wellesley is in the largest group, low (92%), and at its floor, while 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.
Grand River Conservation Authority has mapped flooding for Wellesley (1 study)
Flood studies whose area touches Wellesley, from NRCan’s inventory, each linked to its owner.
One study on the inventory touches Wellesley, Grand River Conservation Authority’s from 2018, and its area can be large, so it says a map exists, not that the town floods.
| Study | By | Year | Status |
|---|---|---|---|
| Grand River Regulatory Floodplain | Grand River Conservation Authority | 2018 | final |
Towns with a flood study on file
69% of towns in Ontario have a flood study, more than Canada’s 58%; Wellesley has one too.
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 Wellesley’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.
Expected shaking damage in Wellesley: $0.016 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.
Earthquake losses in Wellesley, $0.016 per $1,000, are in line with the typical $0.030 (0.5 times).
Shaking damage a year per $1,000 of building value
The typical town in Ontario expects $0.043 a year in shaking damage; Wellesley expects less, $0.016, and Alexandria the most, $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.
Most of Canada’s 2,611 towns (71%) face more earthquake damage than Wellesley.
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 Wellesley 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).
Little radon around Wellesley: 4% of area homes over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
A lower share than most: 4% of tested homes around Wellesley, the typical Canadian town 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Wellesley, 4% of tests topped the guideline, about the same as the typical town in Ontario (4%).
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 Wellesley’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.
Whatever Wellesley’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). · Radon tests: the Waterloo Health Unit
Where to get warnings in Wellesley
Environment and Climate Change Canada issues the weather alerts for Wellesley; 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 Wellesley 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 Wellesley’s neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Wellesley | Low | $0.016 | 4% | Yes |
| New Hamburg 22,890 · 15 km | Low | $0.018 | 4% | Yes |
| Perth East 13,423 · 17 km | Low | $0.018 | 12% | Yes |
| Waterloo 142,450 · 17 km | Low | $0.019 | 4% | Yes |
| Elmira 31,382 · 18 km | Low | $0.020 | 4% | Yes |
| Highland West 12,476 · 18 km | Low | $0.022 | 4% | Yes |
| Westmount 5,048 · 19 km | Low | $0.022 | 4% | Yes |
Nowhere around Wellesley burns more: New Hamburg, the closest rival, is low to its low.
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Wellesley faces
Practical steps for Wellesley’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. The earthquake figure is an expected loss, not a forecast, worked out by NRCan for each census subdivision, Wellesley’s included.
- 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 Wellesley.
- Flood studies aren’t flood zones. Flood studies cover areas of every size, which is why the page lists them for Wellesley without grading them.
- 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 Wellesley until then.
Questions about flooding and hazards in Wellesley
Is Wellesley at risk of wildfire?
No meaningful wildfire history near Wellesley: 0% of nearby land since 1986, band low.
Is radon a problem in Wellesley?
The area’s survey found 4% of 101 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Wellesley.
How big is the earthquake risk in Wellesley?
About $0.016 a year per $1,000 of building value, NRCan’s long-run expectation for Wellesley.
Does Wellesley flood?
A flood study covers Wellesley on Canada’s Flood Map Inventory; open the owner’s map to check a street, since flood isn’t graded.
How is Wellesley’s Hazard risk Grade worked out?
Hazard risk gives Wellesley A, weighing earthquakes and radon and counting wildfire only against it.
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).