Photo: Andre Carrotflower · CC BY-SA 4.0Hazards in Terrace Bay: wildfire low, radon over the guideline in 12% of tested homes
Wildfire is rare near Terrace Bay: 1.9% of the land within 25 km has burned since 1986, a burn rate of 0.05% a year. Earthquakes matter little: NRCan’s model puts building losses at $0.003 a year per $1,000 of value, against $0.030 for the typical town. Hazard risk gives Terrace Bay a grade of A−; its wildfire band pulls it down.
What stands out about Terrace Bay’s hazards
For Terrace Bay, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Terrace Bay faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Terrace Bay: A−
Seismic risk and radon set Terrace Bay’s grade, wildfire can drag it down, and flood mapping stays out of it.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Wildfire is rare near Terrace Bay: 1.9% of the land within 25 km burned since 1986, 3.8% within 5 km
Past fire around Terrace Bay’s homes, from the national burned-area record, with the fuel within 5 km.
Around Terrace Bay fire takes 0.05% of the land in a typical year, the typical Canadian town 0.000%, which is low.
The nearer ring around Terrace Bay is less wooded (74% forest fuel) than the land out to 25 km (82%).
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 872
In the top quarter in Ontario: Terrace Bay ranks 10th of 872 at 0.05% 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.
Some fire is mapped around Terrace Bay, 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.
No flood study is listed for Terrace Bay
What Canada’s Flood Map Inventory lists for Terrace Bay: who studied flooding and where to see their maps.
The inventory has nothing for Terrace Bay, but a local or conservation-authority map may still exist.
Towns with a flood study on file
Terrace Bay has no flood study on file, though 69% of towns in Ontario do (Canada: 58%).
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
The grade leaves flood out, since a study area says nothing about how many of Terrace Bay’s homes are at risk.
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.”
Earthquakes cost buildings in Terrace Bay just $0.003 per $1,000 a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Shaking costs the typical town $0.030 a year; in Terrace Bay it is only $0.003, 0.1 times as much.
Shaking damage a year per $1,000 of building value
Below the middle in Ontario: Terrace Bay’s $0.003 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.
Terrace Bay is among Canada’s quietest towns for earthquakes: 99% of the 2,611 expect more damage.
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).
For Terrace Bay the model prices shaking damage to buildings, nothing more.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Test for radon in Terrace Bay: 12% of area homes were over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · Shared with the rest of the Thunder Bay District Health Unit: radon tests
A higher share than most: 12% of tested homes around Terrace Bay, the typical Canadian town 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Terrace Bay’s area, at 12%, is above the median in Ontario (4%), and 0.9% of its tests passed 600 Bq/m³.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
More high tests than most: Terrace Bay sits in a band that only 22% of Canada’s 2,611 towns share, with 4.6% above.
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.
Health Canada advises testing every home, Terrace Bay’s included, whatever the area’s figure.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Terrace Bay
Environment and Climate Change Canada issues the weather alerts for Terrace Bay; 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 Terrace Bay 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 Terrace Bay’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 |
|---|---|---|---|---|
| Terrace Bay | Low | $0.003 | 12% | None listed |
| Schreiber 1,068 · 12 km | Low | $0.002 | 12% | None listed |
None of the places around has more fire nearby than Terrace Bay (low); Schreiber comes closest (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Terrace Bay faces
Practical steps for Terrace Bay’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?
- Ask the municipality for flood maps.
- 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 Terrace Bay.
- Earthquakes are modelled. The earthquake figure is an expected loss, not a forecast, worked out by NRCan for each census subdivision, Terrace Bay’s included.
- Flood studies aren’t flood zones. The flood inventory points to maps; it is incomplete and not the official source, so ask the municipality about any street in Terrace Bay.
- Radon is a survey. Health Canada’s survey tested some 14,000 homes over three months; until postal-area boundaries are loaded, Terrace Bay takes its 2007 health region’s share.
Questions about flooding and hazards in Terrace Bay
Is Terrace Bay at risk of wildfire?
Some, but Terrace Bay’s low band (1.9% of nearby land burned since 1986, latest 2002) is short of the level that counts.
Is radon a problem in Terrace Bay?
The area’s survey found 12% of 108 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Terrace Bay.
How big is the earthquake risk in Terrace Bay?
NRCan’s model expects shaking to cost buildings in Terrace Bay $0.003 a year for every $1,000 of their value, on average over many years.
Does Terrace Bay flood?
The inventory has 0 studies for Terrace Bay, and an empty list isn’t a clean bill: the municipality holds any flood maps.
How is Terrace Bay’s Hazard risk Grade worked out?
Terrace Bay’s Hazard risk grade is A−, built on earthquakes and radon with a one-sided wildfire input.
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).