A Snow Squall Warning in Canada means intense, localized snowfall is expected to create hazardous conditions, including sudden reductions in visibility and rapidly accumulating snow.
Snow squalls can cause weather and road conditions to change within minutes. Drivers may travel from clear conditions into heavy snow and near-zero visibility over a relatively short distance, making snow squalls particularly dangerous for travel.
Environment and Climate Change Canada issues Snow Squall Warnings when severe weather is happening or expected to happen. Under Canada’s colour-coded weather alert system, Snow Squall Warnings can appear as Yellow, Orange or Red alerts depending on the potential risk.
The seriousness of a snow squall depends on factors such as snowfall intensity, visibility, accumulation, wind, duration, location and the expected impacts.
This guide explains what a Snow Squall Warning means in Canada, why one may be issued, how serious snow squalls can become, what Yellow, Orange and Red alerts mean and what to do when a Snow Squall Warning affects your area.
What Is a Snow Squall Warning?
A Snow Squall Warning is a weather alert issued when intense, localized snowfall is expected to create hazardous conditions.
Snow squalls can produce sudden heavy snow, rapidly reduced visibility and quick accumulations over a relatively small geographic area.
Unlike widespread snowfall events, snow squalls often develop in narrow bands. This means one community may experience intense snow and dangerous travel conditions while a nearby area receives little or no snow.
Conditions can also change very quickly.
Drivers may encounter clear roads before suddenly entering an area of heavy snow and severely reduced visibility.
Environment and Climate Change Canada issues warnings when severe weather is happening or expected to happen. Warnings provide information about expected conditions, potential impacts, timing and actions people can take to reduce their risk.
You can learn more about Snow Squall Warnings and other weather alerts in Canada.
Why Is a Snow Squall Warning Issued?
A Snow Squall Warning is issued to alert people when intense, localized snowfall is expected to create dangerous conditions.
The warning gives people time to monitor changing weather conditions, reconsider travel plans and prepare for rapidly deteriorating visibility and road conditions.
Several factors can influence the seriousness of a snow squall.
Intense Snowfall
Snow squalls can produce very heavy snow over a relatively short period.
Snow may accumulate quickly and cover roads faster than maintenance crews can clear them.
Intense snowfall can also make it difficult for drivers to see roads, vehicles and other hazards.
Sudden Reductions in Visibility
Rapidly changing visibility is one of the most dangerous hazards associated with snow squalls.
Drivers may travel from relatively clear conditions into heavy snow and severely reduced visibility within minutes.
The sudden change can make it difficult to reduce speed or respond safely to vehicles and hazards ahead.
Rapid Snow Accumulation
Snow squalls may produce significant accumulation over a relatively short period.
Roads can quickly become covered and slippery.
The amount of snow may also vary significantly between locations because of the narrow and localized nature of snow squall bands.
Wind
Wind can carry falling and loose snow through the air.
This may further reduce visibility and contribute to drifting snow on roads and open areas.
Duration
Some snow squalls may affect a location for a relatively short period, while persistent snow squall bands can continue affecting the same area for many hours.
Longer-lasting events can result in greater snowfall accumulation and more significant transportation disruptions.
Location
The impacts of a snow squall depend partly on where the band develops and travels.
A snow squall affecting a major highway, urban area or heavily travelled transportation corridor may create more significant impacts than the same weather occurring over a less populated area.
Environment and Climate Change Canada provides additional information about snow squalls and other severe winter weather hazards that can affect Canadians.
How Serious Is a Snow Squall Warning?
A Snow Squall Warning should be taken seriously because snow squalls can cause conditions to deteriorate rapidly and create dangerous travel.
Possible impacts may include:
- Sudden reductions in visibility
- Near-zero visibility
- Rapid snow accumulation
- Snow-covered roads
- Slippery driving conditions
- Multi-vehicle collisions
- Vehicles becoming stranded
- Traffic delays
- Highway closures
- Transportation cancellations
- Localized heavy snowfall
- Snowdrifts
- Disruptions to daily activities
The seriousness of a snow squall depends on the intensity and duration of the snow, visibility, accumulation, wind, location and the vulnerability of the affected area.
Environment and Climate Change Canada uses Weather Impact Guides to assess how hazardous weather may affect daily life, travel, utilities and services, land and structures, human health and community recovery.
Snow Squall Warning Colours in Canada
Snow Squall Warnings in Canada can appear as Yellow, Orange or Red alerts.
The colours move from Yellow to Orange to Red as the potential risk increases.
The colour assigned to a Snow Squall Warning is not determined solely by the amount of snow expected.
Environment and Climate Change Canada considers both the expected impacts of the event and confidence in the forecast when selecting an alert colour.
Yellow Warning – Snow Squall
A Yellow Warning – Snow Squall indicates hazardous weather that may cause damage, disruption or health impacts.
Environment and Climate Change Canada describes the expected impacts of Yellow alerts as generally moderate, localized and/or short-term.
During a Yellow Warning – Snow Squall, possible impacts may include sudden visibility reductions, snow-covered roads, difficult driving conditions and localized transportation disruptions.
Although Yellow represents the lowest of Canada’s three alert colours, snow squalls can still create dangerous conditions.
People in affected areas should monitor current weather information and be prepared for rapidly changing road and visibility conditions.
Orange Warning – Snow Squall
An Orange Warning – Snow Squall indicates a greater level of potential risk than a Yellow alert.
Orange alerts indicate severe weather that is likely to cause significant damage, disruption or health impacts.
The expected impacts may be major, widespread and/or last for several days.
During an Orange Warning – Snow Squall, possible impacts may include extremely dangerous driving conditions, significant snowfall accumulation, highway closures and major transportation disruptions.
Persistent or particularly intense snow squalls may affect communities and transportation corridors for extended periods.
People in affected areas should closely monitor official information, reconsider unnecessary travel and follow instructions from local authorities.
Red Warning – Snow Squall
A Red Warning – Snow Squall represents the highest level of potential risk within Canada’s colour-coded weather alert system.
Red alerts indicate very dangerous and possibly life-threatening weather that is expected to cause extreme damage and disruption.
The expected impacts may be extensive, widespread and prolonged.
During a Red Warning – Snow Squall, exceptionally dangerous conditions may make travel extremely dangerous or impossible.
Possible impacts may include near-zero visibility, major highway closures, stranded vehicles, widespread transportation disruptions and significant impacts on communities.
Red alerts are rare and communicate the most serious potential weather risk within Canada’s alert system.
People in affected areas should follow official information and instructions from local authorities and emergency officials.
Environment and Climate Change Canada provides additional information about Yellow, Orange and Red weather alerts and how the colours communicate increasing levels of potential risk.
Yellow vs Orange vs Red Snow Squall Warnings
The main difference between Yellow, Orange and Red Snow Squall Warnings is the level of potential risk communicated by the alert colour.
A Yellow warning indicates hazardous weather that may cause moderate, localized or short-term impacts.
An Orange warning indicates severe weather that is likely to cause significant impacts that may be major, widespread or last for several days.
A Red warning indicates very dangerous and potentially life-threatening weather that is expected to cause extreme impacts that may be extensive, widespread and prolonged.
| Alert colour | General meaning | Potential snow squall impacts |
|---|---|---|
| Yellow | Moderate, localized or short-term impacts | Sudden poor visibility, snow-covered roads and localized travel disruption |
| Orange | Major, widespread or prolonged impacts | Dangerous travel, highway closures and significant transportation disruption |
| Red | Extreme, widespread and prolonged impacts | Impossible travel, stranded vehicles and extreme disruption |
The warning colour is selected using both expected impacts and forecast confidence.
Environment and Climate Change Canada’s Alert Colour Matrix explains how forecasters combine expected impacts and forecast confidence when selecting Yellow, Orange or Red.
Can the Colour of a Snow Squall Warning Change?
The colour assigned to a Snow Squall Warning reflects the potential risk associated with the expected event.
Environment and Climate Change Canada considers expected weather impacts and forecast confidence when selecting alert colours.
Snow squall intensity, location, duration, expected impacts and forecast confidence may change as the weather develops and new information becomes available.
For this reason, people should continue monitoring the latest Snow Squall Warning rather than relying only on an earlier alert.
Always read the complete warning because it may include additional information about expected snowfall, visibility, timing, affected locations, potential impacts and recommended actions.
Snow Squall Warning vs Snowfall Warning
A Snow Squall Warning and Snowfall Warning both involve potentially hazardous snow, but they describe different types of weather events.
A Snow Squall Warning focuses on intense, localized snowfall that can cause sudden reductions in visibility and rapidly changing road conditions.
A Snowfall Warning generally focuses on significant snowfall associated with a broader or longer-lasting weather event.
Snow squalls may produce large differences in snowfall over relatively short distances.
One community may receive heavy snow while nearby locations experience significantly lighter conditions.
The sudden and localized nature of snow squalls can make them particularly dangerous for drivers.
Snow Squall Warning vs Blizzard Warning
A Snow Squall Warning and Blizzard Warning can both involve severely reduced visibility and dangerous winter travel.
However, the weather conditions associated with the two warnings are different.
A Snow Squall Warning focuses on intense, localized bands of snow that create sudden reductions in visibility and rapid accumulation.
A Blizzard Warning focuses on strong winds combined with falling or blowing snow that create widespread, severely reduced visibility.
Snow squalls are often narrow and localized, while blizzard conditions may affect a much larger geographic area.
Snow Squall Warning vs Blowing Snow Advisory
A Snow Squall Warning and Blowing Snow Advisory can both involve poor visibility caused by snow.
A Snow Squall Warning focuses on intense, localized snowfall that may rapidly reduce visibility and cover roads.
A Blowing Snow Advisory focuses on reduced visibility caused primarily by wind lifting loose snow from the ground.
Significant new snowfall does not necessarily need to occur during a blowing snow event.
Snow Squall Warning vs Winter Storm Warning
A Snow Squall Warning focuses specifically on intense, localized snow bands and the dangerous conditions they create.
A Winter Storm Warning may involve a broader combination of severe winter weather hazards.
Depending on the event, a winter storm may include heavy snow, freezing rain, strong winds, blowing snow or other hazardous winter conditions.
The appropriate warning depends on the weather hazards and expected impacts.
What Can Happen During a Snow Squall Warning?
The impacts of a Snow Squall Warning depend on the intensity, duration and location of the event.
Sudden Visibility Reductions
Visibility may deteriorate rapidly when a snow squall moves across an area.
Drivers may have little time to respond to changing conditions.
Near-Zero Visibility
Intense snowfall and wind may reduce visibility to near zero.
Drivers may be unable to see vehicles, roads, signs and other hazards.
Rapid Snow Accumulation
Snow can accumulate quickly during an intense snow squall.
Roads may become covered faster than maintenance crews can clear them.
Dangerous Driving Conditions
Rapid accumulation and poor visibility can make driving extremely dangerous.
Drivers may lose control, become stranded or collide with other vehicles.
Multi-Vehicle Collisions
Sudden visibility reductions can contribute to multi-vehicle collisions on highways.
Vehicles travelling at highway speeds may have limited time to slow down when entering a snow squall.
Highway Closures
Authorities may close highways and roads when conditions become too dangerous for travel.
Closures may continue after the snow squall ends while roads are cleared and collisions or stranded vehicles are removed.
Transportation Disruptions
Flights, buses and other transportation services may be delayed or cancelled.
Disruptions can continue after the snow squall has moved away.
What Should You Do During a Snow Squall Warning?
The appropriate response to a Snow Squall Warning depends on the alert colour, local conditions, expected impacts and instructions from authorities.
Monitor Current Conditions
Check current weather alerts, forecasts and radar regularly.
Snow squalls can develop, move and change quickly.
Environment and Climate Change Canada provides official weather radar and satellite services that can help people monitor approaching snow.
Reconsider Unnecessary Travel
Consider delaying unnecessary trips when snow squalls are expected to affect your area or travel route.
Conditions may deteriorate rapidly after a trip begins.
Check Road Conditions
Review current highway conditions, closures and transportation information before leaving.
Remember that conditions can vary significantly over relatively short distances.
Reduce Speed
If you encounter a snow squall while driving, reduce your speed gradually and drive according to the conditions.
Sudden braking or steering movements may cause a vehicle to lose traction.
Increase Following Distance
Leave additional space between your vehicle and the vehicle ahead.
Snow-covered roads can increase stopping distances.
Avoid Stopping on the Road
If visibility suddenly deteriorates, avoid stopping in an active traffic lane whenever possible.
Other drivers may have difficulty seeing a stopped vehicle.
Follow Official Information
Continue monitoring Environment and Climate Change Canada and follow road closures, travel recommendations and instructions from local authorities.
The Government of Canada provides additional guidance on how to prepare for winter storms.
Can You Drive During a Snow Squall Warning?
Driving during a Snow Squall Warning can be extremely dangerous.
Snow squalls can cause visibility and road conditions to deteriorate within minutes.
Drivers may encounter intense snow, near-zero visibility, slippery roads and rapidly accumulating snow.
The localized nature of snow squalls also means conditions may appear clear before suddenly becoming dangerous.
Before travelling, check current weather alerts and road conditions.
Consider delaying unnecessary travel when snow squalls are expected.
If you encounter a snow squall while driving, reduce speed, increase following distance and follow road closures and instructions from authorities.
How Long Does a Snow Squall Warning Last?
There is no standard duration for a Snow Squall Warning.
The length of the warning depends on the development, movement and persistence of the snow squall.
Some snow squalls may move through an area relatively quickly.
Other events may produce persistent bands of snow that repeatedly affect the same communities for many hours.
Hazardous conditions may also continue after the snow squall moves away.
Roads may remain covered, highways may remain closed and transportation services may continue experiencing delays.
What Causes Snow Squalls?
Snow squalls develop when atmospheric conditions produce narrow bands of intense snowfall.
In Canada, many snow squalls occur near large bodies of water.
Cold air moving across relatively warmer, unfrozen water can collect heat and moisture.
As the air moves downwind and cools, narrow bands of heavy snow may develop.
This process can produce lake-effect snow squalls near the Great Lakes and other large bodies of water.
The location and intensity of the snow bands depend on factors such as wind direction, temperature differences, atmospheric instability and available moisture.
Where Do Snow Squalls Occur in Canada?
Snow squalls can occur in several parts of Canada, but they are particularly common in areas downwind of large bodies of water.
Communities near the Great Lakes frequently experience lake-effect snow squalls.
Parts of Ontario can receive intense localized snowfall when cold air moves across the Great Lakes and produces narrow snow bands.
Snow squalls can also occur in other regions when atmospheric conditions support intense, localized snowfall.
Because snow squalls are narrow, snowfall amounts and travel conditions may vary dramatically between nearby communities.
How Can You Check Current Snow Squall Warnings?
Current Snow Squall Warnings and other weather alerts can be checked through Environment and Climate Change Canada’s official weather services.
The Weather Information map allows users to view current alert areas and read the complete alert text for affected locations.
You can use the official Weather Information map to check forecasts and alerts across Canada.
The WeatherCAN application also provides official forecasts, alerts and customizable notifications.
Frequently Asked Questions About Snow Squall Warnings
A Snow Squall Warning means intense, localized snowfall is expected to create hazardous conditions, including sudden reductions in visibility and rapidly accumulating snow.
A Snow Squall Warning can indicate dangerous travel conditions. Possible impacts include near-zero visibility, rapid snow accumulation, highway closures and multi-vehicle collisions.
A Yellow Warning – Snow Squall indicates hazardous weather that may cause moderate, localized or short-term impacts.
An Orange Warning – Snow Squall indicates severe weather that is likely to cause significant impacts that may be major, widespread or prolonged.
A Red Warning – Snow Squall represents the highest alert colour and indicates very dangerous and potentially life-threatening weather expected to cause extreme impacts.
A Snow Squall Warning focuses on intense, localized snow that causes sudden visibility reductions and rapidly changing road conditions. A Snowfall Warning generally focuses on significant snow associated with a broader or longer-lasting event.
Snow squalls form when atmospheric conditions create narrow bands of intense snowfall. Many Canadian snow squalls develop when cold air moves across relatively warmer bodies of water.
Snow squalls are particularly common in areas downwind of large bodies of water, including communities near the Great Lakes.
Sources
- https://www.canada.ca/en/services/environment/weather/severeweather/weather-alerts.html
- https://www.canada.ca/en/environment-climate-change/services/seasonal-weather-hazards/severe-winter.html
- https://www.canada.ca/en/services/environment/weather/severeweather/weather-alerts/weather-impact-guides.html
- https://www.canada.ca/en/services/environment/weather/severeweather/weather-alerts/colour-coded-alerts.html
- https://www.canada.ca/en/services/environment/weather/severeweather/weather-alerts/choose-alert-colours.html
- https://www.canada.ca/en/services/environment/weather/radar-satellites.html
- https://www.canada.ca/en/services/policing/emergencies/preparedness/get-prepared/hazards-emergencies/winter-storms/how-prepare.html
- https://www.canada.ca/en/environment-climate-change/services/weather-general-tools-resources/weather-webmapping.html
- https://www.canada.ca/en/environment-climate-change/services/weather-general-tools-resources/weathercan.html