A Freezing Drizzle Advisory in Canada is issued when freezing drizzle is expected to create icy surfaces and hazardous travel conditions.
Freezing drizzle consists of small liquid water droplets that freeze when they come into contact with cold surfaces. This can create a thin, difficult-to-see layer of ice on roads, sidewalks, parking lots and other exposed surfaces.
Even small amounts of ice can make driving and walking dangerous. Roads that appear wet may actually be covered by a thin layer of ice, increasing the risk of vehicle collisions and falls.
Environment and Climate Change Canada issues advisories for certain weather conditions that may cause inconvenience or concern but do not reach the level of a warning.
This guide explains what a Freezing Drizzle Advisory means in Canada, why one is issued, how serious freezing drizzle can become, potential impacts and what to do when an advisory affects your area.
What Is a Freezing Drizzle Advisory?
A Freezing Drizzle Advisory is a weather alert issued when freezing drizzle is expected to create hazardous conditions.
Freezing drizzle occurs when small liquid water droplets fall through the atmosphere and freeze when they come into contact with surfaces that are at or below freezing.
The resulting ice can accumulate on roads, sidewalks, vehicles, trees and other exposed objects.
Because freezing drizzle typically involves very small droplets and light precipitation, the resulting ice may be difficult to see.
Roads and sidewalks may appear wet while actually being covered by a thin layer of ice.
Environment and Climate Change Canada includes Freezing Drizzle Advisories among the official types of weather alerts in Canada.
Why Is a Freezing Drizzle Advisory Issued?
A Freezing Drizzle Advisory is issued to alert people when freezing drizzle is expected to create icy and potentially hazardous conditions.
The advisory gives people time to monitor changing weather, prepare for slippery surfaces and reconsider unnecessary travel.
Several factors contribute to the hazards associated with freezing drizzle.
Ice Accumulation
Freezing drizzle can create a thin layer of ice on exposed surfaces.
Even small amounts of ice can make roads and sidewalks extremely slippery.
Difficult-to-See Ice
One of the primary hazards associated with freezing drizzle is that ice may be difficult to see.
Roads and sidewalks may appear wet even when a thin layer of ice is present.
Hazardous Driving Conditions
Ice can reduce the amount of traction between vehicle tires and the road.
Drivers may have difficulty accelerating, turning and stopping safely.
Slippery Sidewalks
Freezing drizzle can make sidewalks, stairs, parking lots and other walking surfaces hazardous.
The risk of slips and falls may increase.
Changing Weather Conditions
Conditions can change as temperatures rise or fall and precipitation changes between drizzle, freezing drizzle, rain and snow.
The Government of Canada provides additional information about severe winter weather and winter hazards that can affect Canadians.
How Serious Is a Freezing Drizzle Advisory?
A Freezing Drizzle Advisory should be taken seriously because even small amounts of ice can create dangerous conditions.
Possible impacts may include:
- Icy roads
- Slippery sidewalks
- Hazardous driving conditions
- Increased risk of traffic collisions
- Increased risk of slips and falls
- Difficult-to-see ice
- Transportation delays
- Longer travel times
- Ice accumulation on vehicles
- Disruptions to outdoor activities
The seriousness of a freezing drizzle event depends on temperature, duration, ice accumulation, road conditions and location.
Conditions may also vary significantly between nearby areas.
One road may be treated and relatively clear while another road or sidewalk may remain covered by ice.
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.
What Causes Freezing Drizzle?
Freezing drizzle develops when small liquid water droplets fall from clouds and freeze when they contact surfaces at or below freezing.
Several atmospheric conditions contribute to the formation of freezing drizzle.
Small Water Droplets
Drizzle consists of smaller water droplets than regular rain.
These droplets may remain liquid even when air temperatures are below freezing.
Supercooled Water
Supercooled water is liquid water that remains unfrozen despite having a temperature below 0°C.
When supercooled droplets contact cold roads, sidewalks, trees or other surfaces, they can freeze.
Cold Surface Temperatures
Surface temperatures are an important factor in freezing drizzle events.
When roads and other surfaces are at or below freezing, liquid droplets may freeze on contact.
Shallow Clouds
Freezing drizzle can develop in shallow clouds that contain supercooled liquid water but relatively few ice crystals.
The droplets fall from the cloud and freeze when they contact cold surfaces.
Temperature Changes
Changes in temperature can influence whether precipitation falls as drizzle, freezing drizzle, rain or snow.
Small temperature differences near the ground can significantly affect surface conditions.
Freezing Drizzle Advisory vs Freezing Rain Warning
A Freezing Drizzle Advisory and Freezing Rain Warning both involve liquid precipitation that freezes on contact with cold surfaces.
The main difference is the type of precipitation and potential severity of the event.
Freezing drizzle consists of very small droplets and generally produces lighter ice accumulation.
Freezing rain involves larger raindrops and may produce more significant ice accumulation and greater impacts.
A Freezing Rain Warning indicates a more serious freezing precipitation event that may cause dangerous travel conditions, power outages and damage to trees and infrastructure.
Learn more about what a Freezing Rain Warning means in Canada.
Freezing Drizzle Advisory vs Fog Advisory
A Freezing Drizzle Advisory and Fog Advisory communicate different weather hazards.
A Freezing Drizzle Advisory focuses on ice accumulation caused by small liquid droplets freezing on contact with cold surfaces.
A Fog Advisory focuses primarily on significantly reduced visibility caused by dense fog.
Fog and freezing drizzle may sometimes occur during the same weather event.
Learn more about what a Fog Advisory means in Canada.
Freezing Drizzle Advisory vs Snowfall Warning
A Freezing Drizzle Advisory and Snowfall Warning involve different types of winter precipitation.
A Freezing Drizzle Advisory indicates that small liquid droplets are expected to freeze on contact with cold surfaces and create icy conditions.
A Snowfall Warning indicates significant falling snow that is expected to create hazardous conditions and potentially significant impacts.
Both alerts can result in dangerous travel conditions, but the specific hazards are different.
Learn more about what a Snowfall Warning means in Canada.
Freezing Drizzle Advisory vs Winter Storm Warning
A Freezing Drizzle Advisory focuses specifically on freezing drizzle and icy surfaces.
A Winter Storm Warning may involve a combination of severe winter weather hazards.
Depending on the storm, conditions may include heavy snow, freezing rain, strong winds and blowing snow.
A Winter Storm Warning generally communicates a greater level of potential impact than a Freezing Drizzle Advisory.
Learn more about what a Winter Storm Warning means in Canada.
Can a Freezing Drizzle Advisory Become a Warning?
A Freezing Drizzle Advisory does not necessarily become a specific Freezing Drizzle Warning if conditions become more serious.
Instead, a different weather warning may be issued when conditions meet the criteria for another hazard.
For example, if freezing precipitation becomes more significant, a Freezing Rain Warning may be issued when the appropriate conditions are expected.
Other winter weather warnings may also be issued depending on the developing weather event.
People in affected areas should continue monitoring current weather information rather than relying only on an earlier advisory.
Always read the complete alert because updated information may include changes to expected conditions, timing, affected locations, potential impacts and recommended actions.
What Can Happen During a Freezing Drizzle Advisory?
The impacts of a Freezing Drizzle Advisory depend on temperature, duration, ice accumulation and local conditions.
Roads Can Become Icy
Freezing drizzle can create thin layers of ice on roads.
Drivers may encounter slippery conditions even when roads appear wet rather than frozen.
Sidewalks Can Become Slippery
Ice may develop on sidewalks, stairs, driveways and parking lots.
People walking outdoors may face an increased risk of slipping and falling.
Driving Can Become Dangerous
Vehicles may have difficulty maintaining traction on icy roads.
Stopping distances can increase and drivers may lose control when accelerating, braking or turning.
Travel Can Be Delayed
Icy roads may result in slower traffic, collisions and transportation delays.
Road treatment and maintenance operations may also affect travel times.
Ice Can Accumulate on Vehicles
Freezing drizzle may create ice on windshields, mirrors and other vehicle surfaces.
Drivers should completely clear ice from their vehicles before travelling.
What Should You Do During a Freezing Drizzle Advisory?
The appropriate response depends on local conditions and the information included in the advisory.
Read the Complete Advisory
Read the complete alert to understand the expected conditions, timing, affected locations, potential impacts and recommended actions.
Check Conditions Before Travelling
Review current weather and road information before leaving.
Conditions may vary significantly between locations.
Consider Delaying Unnecessary Travel
When significant icing is expected, consider delaying unnecessary trips until conditions improve.
Reduce Your Speed
If you must drive on icy roads, reduce your speed.
Driving more slowly provides additional time to react to changing conditions.
Increase Following Distance
Leave additional space between your vehicle and the vehicle ahead.
Stopping distances may be significantly longer on icy roads.
Watch for Difficult-to-See Ice
Roads and sidewalks may appear wet even when ice is present.
Remain cautious when travelling or walking outdoors.
Wear Appropriate Footwear
Footwear with good traction may reduce the risk of slipping on icy surfaces.
Take additional care when walking on stairs, sidewalks and parking lots.
Monitor Current Weather Information
Continue checking current weather information while the advisory remains in effect.
Environment and Climate Change Canada provides official weather radar and satellite services for monitoring current and approaching weather conditions.
The Government of Canada also provides information about preparing for winter storms.
Can You Drive During a Freezing Drizzle Advisory?
Driving during a Freezing Drizzle Advisory may be hazardous because roads can become covered by thin and difficult-to-see layers of ice.
Before travelling, check current weather and road conditions.
Consider delaying unnecessary trips when significant icing is expected.
If you must drive, reduce your speed, increase your following distance and avoid sudden acceleration, braking or turning.
Remember that bridges, overpasses and other elevated surfaces may freeze before surrounding roads.
What Is the Difference Between Freezing Drizzle and Freezing Rain?
Freezing drizzle and freezing rain both involve supercooled liquid water that freezes when it contacts cold surfaces.
The primary difference is the size of the water droplets.
Freezing drizzle consists of smaller droplets.
Freezing rain consists of larger raindrops.
Freezing rain may produce greater ice accumulation and more significant impacts, although freezing drizzle can still create extremely slippery surfaces and hazardous travel conditions.
Is Freezing Drizzle the Same as Black Ice?
No.
Freezing drizzle is a type of precipitation.
Black ice is a thin and often difficult-to-see layer of ice that develops on roads and other surfaces.
Freezing drizzle may contribute to the formation of difficult-to-see ice, but black ice can also develop through other processes.
For example, moisture on a road may freeze when temperatures decrease below freezing.
How Long Does a Freezing Drizzle Advisory Last?
There is no standard duration for a Freezing Drizzle Advisory.
The length of the advisory depends on temperature, precipitation, ice accumulation, weather patterns and expected impacts.
Some freezing drizzle events may last for several hours.
Others may continue for a longer period when atmospheric conditions remain favourable.
Hazardous conditions may also continue after the freezing drizzle ends because ice can remain on untreated roads and sidewalks.
Where Is Freezing Drizzle Most Common in Canada?
Freezing drizzle can occur in many parts of Canada during the colder months.
The specific frequency and timing vary depending on regional climate and weather patterns.
Areas that frequently experience temperatures near freezing may be vulnerable to freezing drizzle events.
Conditions may also develop before, during or after other winter weather events.
Because even light freezing drizzle can create hazardous surfaces, people should monitor current weather alerts and local conditions throughout the winter.
How Can You Check Current Freezing Drizzle Advisories?
Current Freezing Drizzle Advisories and other weather alerts can be checked through Environment and Climate Change Canada’s official weather services.
The official Weather Information map allows users to check current forecasts and weather alerts across Canada.
The Government of Canada’s WeatherCAN application also provides official forecasts, alerts and customizable notifications.
Frequently Asked Questions About Freezing Drizzle Advisories
A Freezing Drizzle Advisory means freezing drizzle is expected to create icy surfaces and potentially hazardous travel conditions.
A Freezing Drizzle Advisory should be taken seriously because even small amounts of ice can make roads and sidewalks dangerous.
Freezing drizzle occurs when small supercooled liquid water droplets fall and freeze when they contact surfaces at or below freezing.
Yes. Freezing drizzle can create thin and difficult-to-see layers of ice that increase the risk of vehicle collisions and falls.
Freezing drizzle consists of smaller droplets, while freezing rain consists of larger raindrops. Freezing rain may generally produce greater ice accumulation and more significant impacts.
If conditions change and a more significant freezing precipitation event is expected, Environment and Climate Change Canada may issue the appropriate weather warning.
No. Freezing drizzle is a type of precipitation, while black ice is a thin and difficult-to-see layer of ice that can develop on roads and other surfaces.
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/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