Photo: Quintin Soloviev · CC BY 4.0Flood mapping exists for Saint John: 1 on record, latest by Service New Brunswick - GeoNB
Around Saint John, wildfire is practically absent from the record: 0% within 25 km since 1986, 0.000% a year. Earthquake risk in Saint John is ordinary: NRCan’s model puts building losses at $0.033 a year per $1,000 of value, close to the typical town’s $0.030. In Health Canada’s survey, 11% of homes tested in the area exceeded 200 Bq/m³ (6.6% typical). Hazard risk gives Saint John a grade of C+, from earthquakes and radon alone.
What stands out about Saint John’s hazards
Four national sources, each read for Saint John: earthquakes, radon, past fires and flood studies.
What Saint John faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Saint John: C+
Seismic risk and radon set Saint John’s grade, wildfire can drag it down, and flood mapping stays out of it.
Its place: #9 of 60 in New Brunswick and #1,853 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.
Few fires near Saint John: 0% within 5 km, 0% within 25 km
Past fire around Saint John’s homes, from the national burned-area record, with the fuel within 5 km.
Next to the typical Canadian town (0.000% a year), Saint John’s 0.000% is in the low band.
Within 5 km of Saint John, 74% of the land is forest fuel; widen the ring to 25 km and it is 85%.
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 New Brunswick · highest of 60
Among the 60 towns in New Brunswick, Tracadie burns fastest (0.28% a year); Saint John is with the 15 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.
Most of the country’s 2,610 towns are low-band (92%, against 7.5% above); around Saint John, 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.
Saint John is on the flood map inventory: 1 study, by Service New Brunswick - GeoNB
What Canada’s Flood Map Inventory lists for Saint John: who studied flooding and where to see their maps.
A 2020 study by Service New Brunswick - GeoNB covers Saint John, and its map, not the inventory, shows the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Inland Flood Mapping in New Brunswick and Updated Sea-Level Rise and Flooding Estimates for New Brunswick Coastal Sections 2020 | Service New Brunswick - GeoNB | 2020 | final |
Towns with a flood study on file
93% of towns in New Brunswick have a flood study, more than Canada’s 58%; Saint John has one too.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
The grade leaves flood out, since a study area says nothing about how many of Saint John’s homes are at risk.
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 Saint John $0.033 per $1,000 a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
With $0.033 of shaking damage a year per $1,000, Saint John is about even with the typical $0.030 (1.1 times).
Shaking damage a year per $1,000 of building value
Shaking damage around Saint John runs at $0.033 a year, near the $0.036 of the typical town in New Brunswick; St. Stephen has $0.16.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Saint John’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).
The model counts damage to Saint John’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).
Test for radon in Saint John: 11% of area homes were over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · Measured across the Region 2 health region: radon tests
At 11% over the guideline, the area around Saint John beats the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Saint John, 11% of tests were over 200 Bq/m³, under the median in New Brunswick (20%); 1% were over 600.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
More high tests than most: Saint John sits in a band that only 22% of Canada’s 2,611 towns share, with 4.6% above.
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 Saint John; 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 Saint John
Environment and Climate Change Canada issues the weather alerts for Saint John; Alert Ready carries the urgent ones to phones, radio and TV.
| 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. |
In fire season, check CWFIS for danger and active fires around Saint John, and listen to local authorities for orders.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Saint John’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 |
|---|---|---|---|---|
| Saint John | Low | $0.033 | 11% | Yes |
| Grand Bay-Westfield 5,202 · 12 km | Low | $0.031 | 11% | Yes |
| Rothesay 12,626 · 13 km | Low | $0.033 | 11% | Yes |
| Westfield 2,245 · 15 km | Moderate | $0.031 | 11% | Yes |
| Quispamsis 20,240 · 17 km | Low | $0.031 | 11% | Yes |
| Simonds 4,263 · 18 km | Low | $0.026 | 11% | Yes |
Fire is heaviest around Westfield (moderate), against low for Saint John.
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Saint John faces
Practical steps for Saint John’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
- 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 Saint John’s.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Saint John’s 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. NRCan’s inventory says where flood mapping exists, not where water goes; the map’s owner is the authority for Saint John.
- Radon is a survey. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Saint John is its health region’s, the survey’s design unit.
Questions about flooding and hazards in Saint John
Is Saint John at risk of wildfire?
The burned-area record shows next to nothing around Saint John (0% within 25 km since 1986), so its band is low.
Is radon a problem in Saint John?
11% of the 101 homes Health Canada tested around Saint John topped the guideline; your own house needs its own test.
How big is the earthquake risk in Saint John?
NRCan’s model expects shaking to cost buildings in Saint John $0.033 a year for every $1,000 of their value, on average over many years.
How is Saint John’s Hazard risk Grade worked out?
Saint John grades C+ for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Does Saint John flood?
There is flood mapping for Saint John 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).