Photo: William B. Grice · CC BY-SA 4.0Grimsby is on Canada’s flood inventory: 5 listed, led by Niagara Peninsula Conservation Authority
Wildfire isn’t Grimsby’s worry: 0% of the land within 25 km burned since 1986 (0.000% a year). NRCan expects $0.046 of shaking damage a year per $1,000 of buildings in Grimsby, near the typical $0.030. Fewer homes than usual carry radon here, 2% over the guideline where the typical town has 6.6%. Grimsby grades A− for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Grimsby’s hazards
For Grimsby, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Grimsby faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Grimsby: A−
The grade weighs Grimsby’s seismic risk and radon equally, and wildfire is one-sided: a high band counts against a town, a low one earns nothing.
Its place: #442 of 866 in Ontario and #858 of 2,589 Canadian towns.
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 Grimsby: 0% of the land within 25 km burned since 1986, 0% within 5 km
Fires mapped since 1986 around where Grimsby’s residents live, and the fuel next to their homes.
Low by Canadian standards: 0.000% of the land a year around Grimsby, 0.000% for the typical Canadian town.
Land that isn’t forest covers nearly all the ground around Grimsby: forest fuel is 0.1% within 5 km and 0.4% 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
Little or nothing burns around Grimsby in a typical year; 638 of the 871 towns in Ontario share that, and Sioux Lookout leads 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%; Grimsby, 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.
5 flood studies cover Grimsby, the newest from Niagara Peninsula Conservation Authority
Flood studies whose area touches Grimsby, from NRCan’s inventory, each linked to its owner.
The newest of 5 studies covering Grimsby is Niagara Peninsula Conservation Authority ’s, from 2021; open its map to see the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Floodplain Mapping Update in the Towns of Grimsby and Lincoln | Niagara Peninsula Conservation Authority | 2021 | final |
| Spring Creek | Niagara Peninsula Conservation Authority | 2006 | final |
| Forty Mile Creek | Niagara Peninsula Conservation Authority | 1998 | final |
| LakeOntarioOutletNo.25-LINLakeOntario31 | Niagara Peninsula Conservation Authority | final | |
| ThirtyMileCreek | Niagara Peninsula Conservation Authority | final |
Towns with a flood study on file
Mapping in Ontario reaches 69% of towns, Grimsby 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 mapping around Grimsby has come in steps: 3 studies from the 1990s to the 2020s.
Study dates as the NRCan inventory lists them, one count per study touching Grimsby.
Flood mapping is shown for Grimsby to be opened and checked, never turned into a grade.
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 Grimsby: $0.046 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 $0.046 per $1,000, Grimsby’s earthquake risk is about the typical Canadian town’s ($0.030; 1.5 times).
Shaking damage a year per $1,000 of building value
Shaking damage around Grimsby runs at $0.046 a year, near the $0.043 of the typical town in Ontario; 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.
More earthquake risk than most: only 31% of Canada’s 2,611 towns are above Grimsby.
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 Grimsby 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).
2% of homes tested around Grimsby are over the radon guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
Grimsby’s survey area reads 2% over the guideline, under the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Grimsby, 2% of tests were over 200 Bq/m³, under the median in Ontario (4%); 2% were over 600.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Grimsby 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.
Radon varies from house to house in Grimsby, so the survey is a reason to test, not a result for yours.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Radon tests: one figure for all of the Niagara Regional Area Health Unit
Where to get warnings in Grimsby
Alerts for Grimsby 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 Grimsby 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 Grimsby’s neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Grimsby | Low | $0.046 | 2% | Yes |
| Fifty Point 3,690 · 6.3 km | Low | $0.044 | 5% | Yes |
| Industrial 6,690 · 7.9 km | Low | $0.044 | 5% | Yes |
| Trillium 2,967 · 10 km | Low | $0.044 | 5% | None listed |
| Smithville 16,586 · 11 km | Low | $0.060 | 2% | Yes |
| Beamsville 28,356 · 12 km | Low | $0.058 | 2% | Yes |
| Westmeria 2,646 · 12 km | Low | $0.044 | 5% | None listed |
Among its neighbours Grimsby has the most fire on record (low); Fifty Point follows (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Grimsby faces
What to do about the hazards Grimsby 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
- Radon is a survey. Health Canada’s survey tested some 14,000 homes over three months; until postal-area boundaries are loaded, Grimsby takes its 2007 health region’s share.
- Earthquakes are modelled. Seismic risk is NRCan’s model of yearly building losses from shaking, averaged over many years and given for Grimsby’s census subdivision (a neighbourhood shows its city’s).
- Wildfire counts one way. For Grimsby, wildfire means how much nearby land burned in the past forty years, a one-way input that can pull Risk down and nothing more.
- 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 Grimsby.
Questions about flooding and hazards in Grimsby
Is radon a problem in Grimsby?
In Health Canada’s survey, 2% of 100 homes tested in Grimsby’s area were above 200 Bq/m³, though only a test tells you about one house.
How big is the earthquake risk in Grimsby?
Expected earthquake damage in Grimsby comes to $0.046 a year for each $1,000 that buildings are worth.
Is Grimsby at risk of wildfire?
Very little by the national record: Grimsby’s band is low, with 0% of the land within 25 km burned since 1986, so wildfire doesn’t change its grade.
How is Grimsby’s Hazard risk Grade worked out?
Grimsby’s Hazard risk grade is A−, built on earthquakes and radon with a one-sided wildfire input.
Does Grimsby flood?
The inventory lists a study touching Grimsby; whether a given street floods is on that map, not in 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).