Photo: Joe Mabel (on Flickr as Joe Mabel from Seattle, US) · CC BY-SA 3.0Oshawa faces fewer hazards than 89% of Canadian towns
Wildfire barely registers for Oshawa, at 0% of the land within 25 km since 1986 (0.001% a year). For earthquakes Oshawa is middling, $0.033 a year per $1,000 against $0.030 for the typical town. In Health Canada’s survey, just 0% of homes tested in the area exceeded 200 Bq/m³ (6.6% typical). Oshawa grades A for hazard risk, with wildfire counted against it.
What stands out about Oshawa’s hazards
For Oshawa, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Oshawa faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Oshawa grades A for hazard risk
Risk averages earthquakes and radon; wildfire joins only where it pulls the average down, so a town like Oshawa with little fire nearby would get no credit for it.
Its place: #160 of 866 in Ontario and #476 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.
Little of the land around Oshawa has burned: 0% within 5 km, 0% within 25 km since 1986
Past fire around Oshawa’s homes, from the national burned-area record, with the fuel within 5 km.
Next to the typical Canadian town (0.000% a year), Oshawa’s 0.001% is in the low band.
Nothing inside 5 km of Oshawa’s homes has burned since 1986, and the nearest scar is 21 km off.
Forest fuel covers 8.4% of the land close to Oshawa and 15% across 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
Oshawa ranks 83rd of the 871 towns in Ontario for burn rate, at 0.001% a year; Sioux Lookout leads with 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.
7.5% of Canada’s 2,610 towns burn fast enough to rank moderate or above; Oshawa stays low, with 92%.
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.
Flooding around Oshawa is mapped in 3 studies, the newest by Town of Whitby
What Canada’s Flood Map Inventory lists for Oshawa: who studied flooding and where to see their maps.
3 studies on the inventory touch Oshawa, the newest Town of Whitby’s from 2021, and their areas can be large, so they say maps exist, not that the town floods.
| Study | By | Year | Status |
|---|---|---|---|
| Whitby Coastal Flood Hazard, Risk Assessment and Municipal Class Environmental Assessment | Town of Whitby | 2021 | final |
| Corbett Creek Master Drainage Plan | Central Lake Ontario Conservation Authority | 2021 | final |
| Pringle Creek Master Drainage Plan Update | Central Lake Ontario Conservation Authority | 2018 | final · not public |
Towns with a flood study on file
Oshawa is one of the 69% of towns in Ontario with a flood study on file; across Canada it is 58%.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
The studies touching Oshawa lean recent: 2 of 3 date from the 2020s, the first from the 2010s.
Study dates as the NRCan inventory lists them, one count per study touching Oshawa.
Flood studies don’t enter the grade; they are listed so you can open the official map for Oshawa.
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 Oshawa: $0.033 per $1,000 of buildings a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
At $0.033 per $1,000, Oshawa’s earthquake risk is about the typical Canadian town’s ($0.030; 1.1 times).
Shaking damage a year per $1,000 of building value
At $0.033, Oshawa is below the typical town in Ontario ($0.043); Alexandria is highest at $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.
Oshawa’s earthquake risk lands near the centre of Canada’s range; 48% 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).
What a quake does after the shaking, fire, landslides, tsunami, falls outside NRCan’s figure for Oshawa.
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 Oshawa: 0% 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: 0% of tested homes around Oshawa, the typical Canadian town 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Oshawa’s area, at 0%, is below the median in Ontario (4%).
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Oshawa 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.
Health Canada advises testing every home, Oshawa’s included, whatever the area’s figure.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Not measured by town: radon tests (the Durham Regional Health Unit)
Where to get warnings in Oshawa
Alerts for Oshawa 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 Oshawa 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 Oshawa
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Oshawa | Low | $0.033 | 0% | Yes |
| Whitby 162,413 · 7.1 km | Low | $0.036 | 0% | Yes |
| Bowmanville 114,180 · 13 km | Low | $0.028 | 0% | Yes |
| Ajax 141,111 · 15 km | Low | $0.042 | 0% | Yes |
Fire is no heavier anywhere nearby than around Oshawa (low), with Whitby next at low.
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Oshawa faces
What to do about the hazards Oshawa 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. 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 Oshawa.
- Radon is a survey. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Oshawa is its health region’s, the survey’s design unit.
- Earthquakes are modelled. The earthquake figure is an expected loss, not a forecast, worked out by NRCan for each census subdivision, Oshawa’s included.
- 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 Oshawa.
Questions about flooding and hazards in Oshawa
How big is the earthquake risk in Oshawa?
NRCan’s model expects shaking to cost buildings in Oshawa $0.033 a year for every $1,000 of their value, on average over many years.
How is Oshawa’s Hazard risk Grade worked out?
Oshawa’s Hazard risk grade is A, built on earthquakes and radon with a one-sided wildfire input.
Is Oshawa at risk of wildfire?
Less than most of Canada: 0% of the land within 25 km of Oshawa has burned since 1986, the last in 2001, a low band that leaves Risk alone.
Is radon a problem in Oshawa?
In Health Canada’s survey, 0% of 95 homes tested in Oshawa’s area were above 200 Bq/m³, though only a test tells you about one house.
Does Oshawa flood?
There is flood mapping for Oshawa on the national inventory, each study linked to its owner’s map, none of them graded.
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).