Photo: Municipal Affairs and Housing · CC BY 2.0Flood mapping exists for Mississauga: 35 on record, latest by Toronto Regional Conservation Authority
The national fire record shows next to nothing around Mississauga, 0% of the land within 25 km since 1986 (0.000% a year). Seismic risk in Mississauga sits near the middle: $0.040 of expected damage per $1,000 of buildings a year, the typical town $0.030. Fewer homes than usual carry radon here, 0% over the guideline where the typical town has 6.6%.
What stands out about Mississauga’s hazards
For Mississauga, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Mississauga faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Mississauga: the grade is still to come
Two inputs always count for Mississauga, earthquakes and radon; the third, wildfire, counts only against a town.
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 Mississauga: 0% of the land within 25 km burned since 1986, 0% within 5 km
Fires mapped since 1986 around where Mississauga’s residents live, and the fuel next to their homes.
The yearly burn rate around Mississauga is 0.000%, low beside 0.000% for the typical Canadian town.
Little near Mississauga’s homes can carry a forest fire; only 0.5% of the land within 5 km is forest fuel, and 2.9% 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 872
Among the 872 towns in Ontario, Sioux Lookout burns fastest (0.16% a year); Mississauga is with the 639 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.
The low band holds 92% of Canada’s 2,610 towns, and Mississauga sits at its very bottom; only 7.5% are above it.
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 Mississauga is mapped in 35 studies, the newest by Toronto Regional Conservation Authority
Flood studies whose area touches Mississauga, from NRCan’s inventory, each linked to its owner.
35 studies on the inventory touch Mississauga, the newest Toronto Regional Conservation Authority’s from 2021, and their areas can be large, so they say maps exist, not that the town floods.
| Study | By | Year | Status |
|---|---|---|---|
| Toronto Floodline Consolidation | Toronto Regional Conservation Authority | 2021 | final |
| Halton Shoreline Flood Hazard | Conservation Halton | 2020 | final · not public |
| Floodplain Mapping Loyalist Creek | Credit Valley Conservation Authority | 2020 | final · not public |
| Carolyn Creek Floodplain Mapping Study | Credit Valley Conservation Authority | 2020 | final · not public |
| Avonhead Creek | Credit Valley Conservation Authority | 2019 | final · not public |
| Cawthra Creek | Credit Valley Conservation Authority | 2019 | final · not public |
| Clearview Creek | Credit Valley Conservation Authority | 2019 | final · not public |
| Cooksville Creek | Credit Valley Conservation Authority | 2019 | final · not public |
27 more studies on the inventory touch Mississauga.
Towns with a flood study on file
Flood maps are common in Ontario: 69% of towns have one, against 58% nationally, and Mississauga is among them.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Studies touching Mississauga run from the 1990s to the 2020s, with the most in the 2010s: 16 of 35.
Study dates as the NRCan inventory lists them, one count per study touching Mississauga.
Listed, not scored: a flood study proves a map exists, not that Mississauga 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.
Expected shaking damage in Mississauga: $0.040 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.
Nothing unusual about Mississauga’s ground: $0.040 against a typical $0.030, 1.3 times.
Shaking damage a year per $1,000 of building value
About level with the typical town in Ontario: Mississauga’s $0.040 against $0.043; 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.
Mississauga’s earthquake risk lands near the centre of Canada’s range; 43% 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 Mississauga.
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 Mississauga: 0% of area homes over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline. · Measured across the Peel Regional Health Unit: radon tests
Where the typical Canadian town has 6.6% of homes over the guideline, Mississauga’s area has fewer, 0%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
The median in Ontario is 4% over 200 Bq/m³; around Mississauga it is 0%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Mississauga 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.
Whatever Mississauga’s area share, the reading that matters is your own home’s, over a winter.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Mississauga
Alerts for Mississauga 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 Mississauga 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 Mississauga’s neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Mississauga | Low | $0.040 | 0% | Yes |
| Creditview 10,972 · 1.0 km | Low | $0.040 | 0% | Yes |
| DT Core 33,003 · 2.0 km | Low | $0.040 | 0% | Yes |
| Roseborough 54,539 · 2.2 km | Low | $0.040 | 0% | Yes |
| Uptown 12,244 · 2.3 km | Low | $0.040 | 0% | Yes |
| Fairview 7,597 · 2.5 km | Low | $0.040 | 0% | Yes |
| Hurontario 43,877 · 2.6 km | Low | $0.040 | 0% | Yes |
Among its neighbours Mississauga has the most fire on record (low); Creditview follows (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Mississauga faces
What to do about the hazards Mississauga 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. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Mississauga is its health region’s, the survey’s design unit.
- 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 Mississauga.
- Earthquakes are modelled. Seismic risk is NRCan’s model of yearly building losses from shaking, averaged over many years and given for Mississauga’s census subdivision (a neighbourhood shows its city’s).
- Wildfire counts one way. For Mississauga, wildfire means how much nearby land burned in the past forty years, a one-way input that can pull Risk down and nothing more.
Questions about flooding and hazards in Mississauga
Does Mississauga flood?
There is flood mapping for Mississauga on the national inventory, each study linked to its owner’s map, none of them graded.
Is radon a problem in Mississauga?
Around Mississauga, 90 survey homes were tested and 0% came in over 200 Bq/m³, a guide to the area, not to any one home.
How is Mississauga’s Hazard risk Grade worked out?
Not yet: Canada’s grades come with its first grading run, when Risk will weigh earthquakes and radon in Mississauga, with wildfire able only to lower it.
Is Mississauga at risk of wildfire?
The burned-area record shows next to nothing around Mississauga (0% within 25 km since 1986), so its band is low.
How big is the earthquake risk in Mississauga?
About $0.040 a year per $1,000 of building value, NRCan’s long-run expectation for Mississauga.
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).