What Does an Orange Snowfall Warning Mean?
An orange snowfall warning means that heavy snow is occurring or expected, with accumulations likely to cause significant travel disruptions and potentially damage property.
Environment and Climate Change Canada uses colour-coded warnings to communicate the expected impact of severe weather. An orange warning indicates that forecasters expect major impacts and have high or very high confidence in the forecast, or expect extreme impacts with moderate or high confidence.
The orange designation is not determined by a specific snowfall amount. Forecasters consider the expected accumulation, snowfall rate, location, timing and potential consequences for affected communities.
For example, a major snowfall during the morning commute may cause more disruption than a similar amount of snow falling overnight.
Snowfall Warning Colours in Canada
Canada uses three warning colours to communicate the expected severity of weather events.
| Warning Colour | Meaning |
|---|---|
| Yellow | Hazardous weather that may cause moderate, localized or short-term disruptions. |
| Orange | Severe weather likely to cause major, widespread or longer-lasting disruptions. |
| Red | Extremely dangerous weather expected to cause extensive and prolonged disruptions. |
Orange snowfall warnings are uncommon and indicate that heavy snow may significantly affect transportation, property and daily activities.
What Causes an Orange Snowfall Warning?
Heavy snowfall develops when moist air rises, cools and produces snow in clouds where temperatures are sufficiently cold.
Several weather conditions can produce significant snowfall across Canada:
- Low-pressure systems: Large storm systems can transport moisture across vast areas, producing widespread snowfall over several hours or days.
- Winter weather fronts: When different air masses meet, rising air can produce bands of moderate to heavy snow.
- Lake-effect snowfall: Cold air passing over relatively warmer, unfrozen lakes can absorb moisture and produce heavy snowfall downwind.
- Mountain terrain: Moist air forced upward over mountains cools and can produce substantial snowfall at higher elevations.
The severity of a snowfall event depends on the amount of moisture available, atmospheric temperatures, how quickly the snow falls and how long the weather system remains over an area.
What Should You Expect During an Orange Snowfall Warning?
An orange snowfall warning indicates that significant snow accumulation may create dangerous conditions and interfere with transportation and everyday activities.
Possible impacts include:
- Dangerous road conditions: Heavy snow can cover roads quickly, reducing traction and increasing the likelihood of collisions.
- Highway closures: Major highways and rural roads may become impassable or be closed until snow removal crews can clear them.
- Significant travel delays: Snow-covered roads, collisions and reduced visibility can cause lengthy delays for motorists and public transportation.
- Property damage: Heavy accumulations can place additional weight on roofs, sheds and other structures.
- Falling trees and branches: Wet, heavy snow can accumulate on trees, causing branches to break or trees to fall.
- Power outages: Snow-covered branches may fall onto power lines, interrupting electrical service.
- Difficult snow removal: Large accumulations can make clearing driveways, sidewalks and parking lots more challenging.
Conditions can vary considerably across the affected region. Communities at higher elevations or directly beneath persistent snow bands may receive much more snow than nearby areas.
How Much Snow Is Needed for an Orange Snowfall Warning?
There is no single snowfall amount that automatically results in an orange snowfall warning across Canada.
Environment and Climate Change Canada uses an impact-based warning system that considers the expected consequences of the weather and the confidence of the forecast.
An orange warning may be issued when forecasters expect heavy snow to cause dangerous travel conditions, multiple vehicle collisions, road closures, prolonged delays or damage to property.
Several factors influence how much disruption a snowfall event may cause:
- Snowfall rate: Snow falling rapidly can cover roads faster than crews can clear them.
- Total accumulation: Large amounts of snow can block roads, driveways and entrances.
- Snow consistency: Wet, heavy snow places more weight on trees, power lines and roofs than lighter, drier snow.
- Timing: Heavy snowfall during busy commuting periods may cause greater travel disruptions.
- Existing snow cover: Additional snowfall can make already difficult conditions worse.
As a result, two communities receiving the same amount of snowfall may experience different levels of disruption.
What Should You Do During an Orange Snowfall Warning?
During an orange snowfall warning, residents should avoid unnecessary travel and prepare for potentially difficult winter conditions.
Recommended precautions include:
- Postpone unnecessary travel. Heavy snow can make roads dangerous and cause unexpected closures.
- Check highway conditions. Consult your provincial road information service before driving.
- Monitor weather warnings. Follow Environment and Climate Change Canada for updated snowfall forecasts, affected regions and expected timing.
- Prepare essential supplies. Keep drinking water, medications, flashlights, charged devices and other necessities available.
- Clear snow carefully. Take breaks when shovelling, avoid overexertion and seek assistance if needed.
- Keep important exits accessible. Clear snow from doorways and necessary walkways when it is safe to do so.
- Stay away from damaged trees and power lines. Heavy snow can cause branches and electrical lines to fall without warning.
If you must travel, keep an emergency kit in your vehicle containing warm clothing, blankets, drinking water, a flashlight and a charged phone.
What If Snow Starts Accumulating on Your Roof?
Heavy snow can place significant weight on a roof, particularly when the snow is wet or accumulates over multiple storms.
Signs of possible structural problems may include unusual cracking sounds, visible sagging or new difficulty opening doors and windows.
If you suspect that your roof is under excessive strain, stay away from the affected area and contact a qualified professional.
Avoid climbing onto a snow-covered roof, as slippery surfaces and accumulated snow can make the work dangerous.
How Long Does an Orange Snowfall Warning Last?
An orange snowfall warning does not have a fixed duration.
Some weather systems produce heavy snow for several hours, while larger winter storms may continue for a day or longer.
The warning remains in effect while hazardous conditions are occurring or expected. Environment and Climate Change Canada may update or end the warning as snowfall decreases or the expected impacts change.
Road conditions can remain dangerous after snowfall ends, particularly where significant accumulations require extensive clearing.
Highway closures, transportation delays and snow removal operations may continue after the warning has been lifted.
Frequently Asked Questions
A yellow snowfall warning indicates hazardous conditions that may cause moderate or localized disruptions. An orange snowfall warning indicates a greater risk of major impacts, including dangerous roads, multiple vehicle collisions, highway closures and significant property damage.
There is no fixed snowfall amount that automatically triggers an orange warning across Canada. Environment and Climate Change Canada considers the expected impacts, forecast confidence and local conditions when determining the warning colour.
A snowfall warning focuses on significant snow accumulation that may create dangerous conditions. A snow squall warning concerns intense, localized bands of snow that can rapidly reduce visibility and make driving dangerous. Snow squalls can develop suddenly and may affect much smaller areas.
Driving during an orange snowfall warning can be dangerous because of accumulating snow, slippery roads and reduced visibility. Avoid unnecessary travel and check official highway conditions before leaving. Follow all road closures and instructions from local authorities.
You can check current snowfall warnings through Environment and Climate Change Canada’s weather website or the WeatherCAN mobile app. Both provide official warnings, affected regions, expected snowfall amounts and updates as conditions develop. For current highway conditions and road closures, consult your provincial road information service.