Photo: Unknown. Canada. Department of National Defence. · Public domainFlood mapping exists for Southwold: 1 on record, latest by Kettle Creek Conservation Authority
For Southwold, wildfire history is close to nil: 0% of nearby land since 1986, 0.000% a year. Earthquake risk in Southwold is ordinary: NRCan’s model puts building losses at $0.021 a year per $1,000 of value, close to the typical town’s $0.030. Southwold’s survey area, 7.5% over the radon guideline, is close to the typical town’s 6.6%. Hazard risk gives Southwold a grade of B+, from earthquakes and radon alone.
What stands out about Southwold’s hazards
Four national sources, each read for Southwold: earthquakes, radon, past fires and flood studies.
What Southwold faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Southwold grades B+ for hazard risk
Two inputs always count for Southwold, earthquakes and radon; the third, wildfire, counts only against a town.
Its place: #473 of 866 in Ontario and #919 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 Southwold: 0% of the land within 25 km burned since 1986, 0% within 5 km
Past fire around Southwold’s homes, from the national burned-area record, with the fuel within 5 km.
Next to the typical Canadian town (0.000% a year), Southwold’s 0.000% is in the low band.
With 0.3% forest fuel within 5 km and 0.4% within 25 km, the land around Southwold gives a fire little to burn.
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); Southwold 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.
Southwold shares the low band with 92% of Canada’s 2,610 towns, its burn rate rounding to nothing; 7.5% burn faster.
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.
Southwold is on the flood map inventory: 1 study, by Kettle Creek Conservation Authority
What Canada’s Flood Map Inventory lists for Southwold: who studied flooding and where to see their maps.
Kettle Creek Conservation Authority studied flooding in an area that includes Southwold (2024); open its map to see which streets lie in a flood zone.
| Study | By | Year | Status |
|---|---|---|---|
| Dodd Creek Enhanced Riverine Floodplain Mapping | Kettle Creek Conservation Authority | 2024 | final |
Towns with a flood study on file
Its flood study puts Southwold 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.
Listed, not scored: a flood study proves a map exists, not that Southwold floods.
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.
Ordinary seismic risk in Southwold: $0.021 per $1,000 of buildings a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Nothing unusual about Southwold’s ground: $0.021 against a typical $0.030, 0.7 times.
Shaking damage a year per $1,000 of building value
Earthquake risk in Ontario peaks in Alexandria ($0.21); Southwold, at $0.021, is below 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.
Southwold sits mid-range among Canada’s 2,611 towns: 63% expect more shaking 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).
Roads, pipes and bridges aren’t in Southwold’s figure, nor landslides or tsunami: it is buildings and shaking.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Some radon around Southwold: 7.5% of area homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline.
At 7.5% over the guideline, the area around Southwold is about level with the typical Canadian town’s 6.6%. Behind radon tests sits data gathered across the Elgin-St. Thomas Health Unit, with Southwold one part of it.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Southwold, 7.5% of tests were over 200 Bq/m³ and 1.1% over 600, against a median of 4% in Ontario.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
A middling share of high tests puts Southwold with 37% of Canada’s 2,611 towns, below 26% of them.
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 survey sampled homes around Southwold; it can’t tell you your basement’s level.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Southwold
Alerts for Southwold 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 Southwold 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)
Hazards in the places around Southwold
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Southwold | Low | $0.021 | 7.5% | Yes |
| Oneida 41 1,565 · 12 km | Low | $0.018 | 1.8% | None listed |
| St. Thomas 49,388 · 13 km | Low | $0.023 | 7.5% | Yes |
| Central Elgin 15,230 · 14 km | Low | $0.020 | 7.5% | Yes |
| Dutton 4,686 · 17 km | Low | $0.020 | 7.5% | None listed |
| Lambeth 2,609 · 19 km | Low | $0.020 | 1.8% | None listed |
Nowhere around Southwold burns more: Oneida 41, 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 Southwold faces
What to do about the hazards Southwold 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
- 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 Southwold.
- Radon is a survey. Health Canada’s survey tested some 14,000 homes over three months; until postal-area boundaries are loaded, Southwold takes its 2007 health region’s share.
- 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 Southwold’s.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Southwold’s homes burned each year from 1986 to 2025, past fire rather than a forecast, and it can only lower Risk.
Questions about flooding and hazards in Southwold
How is Southwold’s Hazard risk Grade worked out?
Hazard risk gives Southwold B+, weighing earthquakes and radon and counting wildfire only against it.
Is Southwold at risk of wildfire?
Very little by the national record: Southwold’s band is low, with 0% of the land within 25 km burned since 1986, so wildfire doesn’t change its grade.
How big is the earthquake risk in Southwold?
In NRCan’s seismic model, Southwold’s buildings lose $0.021 per $1,000 of value in an average year.
Does Southwold flood?
The inventory lists a study touching Southwold; whether a given street floods is on that map, not in the grade.
Is radon a problem in Southwold?
Around Southwold, 93 survey homes were tested and 7.5% came in over 200 Bq/m³, a guide to the area, not to any one home.
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).