Photo: Gogerr · CC BY-SA 4.0A flood study covers St. Catharines: 10 on the national inventory, the newest from Niagara Peninsula Conservation Authority
Wildfire isn’t St. Catharines’ worry: 0% of the land within 25 km burned since 1986 (0.000% a year). Earthquakes add more: NRCan’s model puts building losses at $0.066 a year per $1,000 of value, against $0.030 for the typical town. In Health Canada’s survey, just 2% of homes tested in the area exceeded 200 Bq/m³ (6.6% typical). St. Catharines grades B+ for hazard risk; wildfire is low here, so it earns no credit.
What stands out about St. Catharines’s hazards
Four national sources, each read for St. Catharines: earthquakes, radon, past fires and flood studies.
What St. Catharines faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in St. Catharines: B+
The grade weighs St. Catharines’ seismic risk and radon equally, and wildfire is one-sided: a high band counts against a town, a low one earns nothing.
Its place: #475 of 866 in Ontario and #923 of 2,589 Canadian towns.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. Small fires and grass fires are largely missing from the national burned-area record.
Wildfire is rare near St. Catharines: 0% of the land within 25 km burned since 1986, 0% within 5 km
Fires mapped since 1986 around where St. Catharines’ residents live, and the fuel next to their homes.
Low by Canadian standards: 0.000% of the land a year around St. Catharines, 0.000% for the typical Canadian town.
Land that isn’t forest covers nearly all the ground around St. Catharines: forest fuel is 1.5% within 5 km and 0.8% 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
To three decimals the burn rate around St. Catharines is zero, as for 638 of the 871 towns in Ontario, while Sioux Lookout reaches 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.
Most of the country’s 2,610 towns are low-band (92%, against 7.5% above); around St. Catharines, burning rounds to zero.
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.
10 flood studies cover St. Catharines, the newest from Niagara Peninsula Conservation Authority
Flood studies whose area touches St. Catharines, from NRCan’s inventory, each linked to its owner.
10 studies on the inventory touch St. Catharines, the newest Niagara Peninsula Conservation Authority’s from 2020, and their areas can be large, so they say maps exist, not that the town floods.
| Study | By | Year | Status |
|---|---|---|---|
| Walker's Creek & Beamer Creek | Niagara Peninsula Conservation Authority | 2020 | final |
| Richardsons and Francis Creek,West St. Catharines | Niagara Peninsula Conservation Authority | 2019 | final |
| Walker Beamer Creek | Niagara Peninsula Conservation Authority | 2019 | final |
| Niagara-On-The-Lake | Niagara Peninsula Conservation Authority | 2008 | final |
| Sixteen Mile Creek | Niagara Peninsula Conservation Authority | 2007 | final |
| Eighteen Mile Creek | Niagara Peninsula Conservation Authority | 2005 | final |
| Upper Twelve Mile Creek | Niagara Peninsula Conservation Authority | 2005 | final |
| City of St. Catherines | Niagara Peninsula Conservation Authority | 1995 | final |
2 more studies on the inventory touch St. Catharines.
Towns with a flood study on file
Its flood study puts St. Catharines with 69% of towns in Ontario; Canada’s share is 58%.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
The busiest decade for flood studies around St. Catharines was the 2000s (4 of 8); they run from the 1990s to the 2020s.
Study dates as the NRCan inventory lists them, one count per study touching St. Catharines.
Flood studies don’t enter the grade; they are listed so you can open the official map for St. Catharines.
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.
High seismic risk in St. Catharines: $0.066 per $1,000 of buildings a year
NRCan’s seismic risk model: the damage shaking is expected to do to buildings each year, on average over many years.
The typical town loses $0.030 a year to shaking; St. Catharines loses $0.066, 2.2 times as much.
Shaking damage a year per $1,000 of building value
Earthquake risk in Ontario peaks in Alexandria ($0.21); St. Catharines, at $0.066, sits above the median of $0.043.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
St. Catharines sits above most of Canada’s 2,611 towns on earthquake risk; 29% 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 St. Catharines’ 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).
2% of homes tested around St. Catharines are over the radon guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
St. Catharines’ area, at 2%, is below the 6.6% of the typical Canadian town, though any one home can still be high.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Below the typical town in Ontario (4%) at 2%, the area around St. Catharines still had 2% of tests over 600 Bq/m³.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Radon rarely tops the guideline around St. Catharines, as for 37% of Canada’s 2,611 towns; 63% see 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.
The share describes the area, not a house: in St. Catharines as anywhere, test to be sure.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Data for radon tests covers the Niagara Regional Area Health Unit
Weather and fire alerts for St. Catharines
Alerts for St. Catharines 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 St. Catharines 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)
Hazards in the places around St. Catharines
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| St. Catharines | Low | $0.066 | 2% | Yes |
| Thorold 33,844 · 7.3 km | Low | $0.061 | 2% | Yes |
| Niagara-on-the-Lake 20,080 · 11 km | Low | $0.062 | 2% | Yes |
| Niagara Falls 113,983 · 14 km | Low | $0.066 | 2% | Yes |
| Beamsville 28,356 · 15 km | Low | $0.058 | 2% | Yes |
| Pelham 19,980 · 16 km | Low | $0.055 | 2% | Yes |
St. Catharines’ low band tops its neighbours; Thorold is next (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what St. Catharines faces
What to do about the hazards St. Catharines 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. The wildfire figure is the share of land within 25 km of St. Catharines’ homes burned each year from 1986 to 2025, past fire rather than a forecast, and it can only lower Risk.
- 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 St. Catharines.
- 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 St. Catharines’.
- Radon is a survey. Health Canada’s survey tested some 14,000 homes over three months; until postal-area boundaries are loaded, St. Catharines takes its 2007 health region’s share.
Questions about flooding and hazards in St. Catharines
Is St. Catharines at risk of wildfire?
The burned-area record shows next to nothing around St. Catharines (0% within 25 km since 1986), so its band is low.
Is radon a problem in St. Catharines?
Around St. Catharines, 100 survey homes were tested and 2% came in over 200 Bq/m³, a guide to the area, not to any one home.
How big is the earthquake risk in St. Catharines?
About $0.066 a year per $1,000 of building value, NRCan’s long-run expectation for St. Catharines.
How is St. Catharines’s Hazard risk Grade worked out?
St. Catharines grades B+ for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Does St. Catharines flood?
The inventory lists a study touching St. Catharines; 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).