Photo: GTD Aquitaine · Public domainA flood study covers Guildwood: 1 on the national inventory, the newest from Toronto Regional Conservation Authority
Wildfire isn’t Guildwood’s worry: 0% of the land within 25 km burned since 1986 (0.001% a year). Seismic risk in Guildwood sits near the middle: $0.043 of expected damage per $1,000 of buildings a year, the typical town $0.030. In Health Canada’s survey, just 2.7% of homes tested in the area exceeded 200 Bq/m³ (6.6% typical). Hazard risk gives Guildwood a grade of A−; its wildfire band pulls it down.
What stands out about Guildwood’s hazards
Four national sources, each read for Guildwood: earthquakes, radon, past fires and flood studies.
What Guildwood faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Guildwood grades A− for hazard risk
For Guildwood, Risk will be the average of earthquakes and radon, with wildfire added only if it makes the average worse.
Its place: #285 of 866 in Ontario and #700 of 2,589 Canadian towns.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. Only 74 homes were tested in the survey area, so the radon share is rough. Small fires and grass fires are largely missing from the national burned-area record.
Few fires near Guildwood: 0% within 5 km, 0% within 25 km
Past fire around Guildwood’s homes, from the national burned-area record, with the fuel within 5 km.
The land within 25 km of Guildwood burns at 0.001% a year on average, the low band; the typical Canadian town: 0.000%.
Since 1986 the nearest fire to Guildwood’s homes came within 12 km, never inside 5 km.
Forest makes up 1% of the land within 5 km of Guildwood and 3.5% 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
At 0.001% a year, Guildwood is near the top in Ontario: 83rd of 871, behind Sioux Lookout (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 Guildwood, 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.
Toronto Regional Conservation Authority has mapped flooding for Guildwood (1 study)
What Canada’s Flood Map Inventory lists for Guildwood: who studied flooding and where to see their maps.
Toronto Regional Conservation Authority holds the flood mapping that covers Guildwood (2021), linked below.
| Study | By | Year | Status |
|---|---|---|---|
| Toronto Floodline Consolidation | Toronto Regional Conservation Authority | 2021 | final |
Towns with a flood study on file
Flood maps are common in Ontario: 69% of towns have one, against 58% nationally, and Guildwood is among them.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood mapping is shown for Guildwood 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.
Earthquakes cost buildings in Guildwood $0.043 per $1,000 a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Guildwood’s $0.043 is close to the typical town’s $0.030 (1.4 times as much).
Guildwood shares its earthquake risk numbers with the rest of the city of Toronto.
Shaking damage a year per $1,000 of building value
Neither high nor low in Ontario: Guildwood’s $0.043 sits by the median of $0.043, while Alexandria reaches $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.
Guildwood’s earthquake risk lands near the centre of Canada’s range; 36% of the 2,611 towns 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 model counts damage to Guildwood’s buildings and their occupants from shaking only: not liquefaction, landslides, tsunami or fires after a quake.
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 Guildwood: 2.7% of area homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline.
A lower share than most: 2.7% of tested homes around Guildwood, the typical Canadian town 6.6%. Figures for radon tests are published for the City of Toronto Health Unit as a whole, not for Guildwood alone.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
The median in Ontario is 4% over 200 Bq/m³; around Guildwood it is 2.7%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Few tests over the guideline: Guildwood shares the bottom band with 37% of Canada’s 2,611 towns, below the other 63%.
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.
Basements, soil and how a house is sealed decide its radon, so in Guildwood only a test can say.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Guildwood
Alerts for Guildwood 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 Guildwood 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 Guildwood’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 |
|---|---|---|---|---|
| Guildwood | Low | $0.043 | 2.7% | Yes |
| Scarborough Village 16,774 · 1.7 km | Low | $0.043 | 2.7% | Yes |
| Golfdale-Cedarbrae-Woburn 27,429 · 2.1 km | Low | $0.043 | 2.7% | Yes |
| West Hill 28,414 · 2.2 km | Low | $0.043 | 2.7% | Yes |
| Morningside 17,708 · 3.6 km | Low | $0.043 | 2.7% | Yes |
| Woburn North 26,662 · 4.0 km | Low | $0.043 | 2.7% | Yes |
| Eglinton East 22,820 · 4.1 km | Low | $0.043 | 2.7% | Yes |
Among its neighbours Guildwood has the most fire on record (low); Scarborough Village follows (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Guildwood faces
Practical steps for Guildwood’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
- Radon is a survey. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Guildwood is its health region’s, the survey’s design unit.
- Earthquakes are modelled. NRCan models what earthquakes would cost buildings each year on average, subdivision by subdivision; Guildwood’s figure is its subdivision’s.
- Flood studies aren’t flood zones. NRCan’s inventory says where flood mapping exists, not where water goes; the map’s owner is the authority for Guildwood.
- Wildfire counts one way. Wildfire is read from the national burned-area record around Guildwood’s homes since 1986, a history of fire that may lower Risk but never raises it.
Questions about flooding and hazards in Guildwood
Is Guildwood at risk of wildfire?
Some, but Guildwood’s low band (0% of nearby land burned since 1986, latest 2001) is short of the level that counts.
How big is the earthquake risk in Guildwood?
In NRCan’s seismic model, Guildwood’s buildings lose $0.043 per $1,000 of value in an average year.
Does Guildwood flood?
There is flood mapping for Guildwood on the national inventory, each study linked to its owner’s map, none of them graded.
How is Guildwood’s Hazard risk Grade worked out?
Guildwood’s Hazard risk grade is A−, built on earthquakes and radon with a one-sided wildfire input.
Is radon a problem in Guildwood?
The area’s survey found 2.7% of 74 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Guildwood.
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).