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Winter weather: Snow and ice

Unincorporated King County snow and ice response Winter Weather Response Map - plowed and sanded roads. Check your snow routes. Prepare for winter storms. Frequently asked questions. Snow and ice videos.

Check your snow route

Will your route be clear this winter?

King County plows and treats 583 miles of designated snow and ice routes. If you do not live on a designated route, be prepared for the possibility you may need to stay home and avoid driving for up to several days during a major winter storm.

Primary routes for plowing and sanding in a countywide snow and ice event

2021-22 King County snow routes.
>> Map of 2021-22 snow routes PDF 2MB
>> Text list of 2021-22 snow routes WORD 76KB

Be ready!




Preparing for snow and ice videos
















Be ready for freezing temperatures and snowfall

Be prepared

Resources for emergency preparedness

Winter storm tip sheets from the Washington State Department of Health:

Emergency preparedness information from other agencies:

Frequently-asked questions about snow and ice response

View a map of 2021-22 snow routes PDF 2MB. We plow and sand the roads that are designated on the snow route map. Our crews must prioritize primary snow routes, such as main arterials and major roads and may not be able to reach residential streets, even if they are on a designated snow route. In most cases, communities should not expect roads other than designated snow routes to be plowed and sanded in any type of storm. If your area is not on a designated snow route, be prepared to wait up to several days and, when possible, avoid driving, in severe weather. If you need life-safety emergency access plowing, or are medically vulnerable and in need of treatment, call 9-1-1.
There are 583 miles of designated snow and ice routes in unincorporated King County. These snow and ice routes include high-volume roads that deliver traffic to and from the highway, lifeline emergency routes, transit routes and minor collector roads that serve densely populated areas.

Phone: 206-477-8100; Relay: 711
Email: maint.roads@kingcounty.gov
King County plows and sands roads that are on our designated snow routes. During large, countywide events, crews must prioritize plowing main arterials and major roads and may not be able to reach snow routes on residential streets. If your road is on a snow route but has not been plowed, you may call or email our 24/7 Road Helpline to request snow removal service, or to report downed trees, or any other winter weather emergency. In most cases, communities should not expect roads other than designated snow routes to be plowed and sanded in any type of storm. If you need life-safety emergency access plowing, or are medically vulnerable and in need of treatment, call 9-1-1.
Yes. View our Winter Weather Response Map to track recently plowed areas. The map does not post actual real time locations for two reasons: to allow time for sand and salt to sit on the roadway and do its work; and to prevent drivers from following our plows. Tailgating a snowplow is not safe.
King County does not have the resources to plow all 1500 miles of road in unincorporated King County. Make sure to check the snow route map to see if your road will be plowed. If you do not live on a designated route, be prepared to stay home and avoid driving for up to several days during a major winter storm. If you need life-safety emergency access plowing, or are medically vulnerable and in need of treatment, call 9-1-1.

Snow routes are categorized according to priority:

  • Category 1 routes are plowed first, then category 2, category 3 and so on.
  • Category 1 routes include main roadways (primary arterials, transit routes, lifeline routes) providing regional connections between communities.
  • Category 2 routes are main roadways (primary arterials, main thoroughfares, and arterials leading to state highways) and minor arterials feeding densely populated areas.
  • Category 3 routes are minor collectors that lead to and connect with Category 1 and 2 routes. These routes provide continuity between towns, cities, and large subdivisions. Category 4 routes are secondary commuter routes that connect Category 1, 2, and 3 routes along with other jurisdictions.
There are a few reasons why only half of the road, or a section of road is plowed. Our categorized snow routes are not contiguous. There are times when we need to travel on lower category road in order to reach the higher category road. As a result, there may be occasions where a section of a lower category snow route may be plowed or receive treatment when drivers need to drive and clear that section of road in order to reach a higher category snow route. Another reason for half-road treatment is when the Office of Emergency Management requests us to plow or treat a road for emergency response.
Countywide events often require us to dispatch all of our available snow response resources to plow and sand as many miles of designated snow routes as possible.

A countywide snow and ice event occurs when snow and ice response crews are needed in most or all areas of unincorporated King County at the same time.
A localized snow and ice event occurs when snow and ice response crews are needed in one or two areas of unincorporated King County at the same time.
At times, snow may accumulate faster than our plows can keep up with; however county crews will plow and sand the primary routes throughout the snow event. The county's primary (category 1) snow routes connect police and fire stations, hospitals and emergency centers. Category 2, category 3 and category 4 routes will be plowed and sanded in descending order after category 1 routes.

Hazards in the roadway, such as fallen trees or downed power lines, extraordinary public safety needs or equipment breakdowns could delay snow-clearing work.

You can check our Winter Weather Response Map to see where our plows have recently cleared away snow.
The county does not have the resources to plow all 1500 miles of road in unincorporated King County.

We will work with first responders to clear roads that are outside of our designated snow routes during extraordinary public safety emergencies. However, in most cases, communities should not expect roads other than designated snow routes to be plowed and sanded in any type of storm.
The Washington State Department of Transportation (WSDOT) manages state highways and freeways. Check WSDOT's snow and ice page for news and information.
For snow removal in cities and towns in King County, visit the city or town's website (here's a list of links) and look for snow and ice information or plow routes and maps.
If needed, snowplows will be pulled off routes to help emergency vehicles gain access into neighborhoods for life and safety emergency response. Emergency snowplowing is coordinated through the 9-1-1 center and the Office of Emergency Management.
King County employs year-round licensed and trained road maintenance crews that are experienced at operating snow and ice removal equipment. Crew members actively roam unincorporated King County roadways around the clock to monitor and respond to winter weather such as ice and snow, flooding and downed trees.

King County crews from other departments such as the Department of Natural Resources and Parks are also trained to drive plows and help clear and sand roads within our designated snow route area when needed.
No. The County cannot authorize private community members, residents or private snow removal contractors to plow public roads. Plowing public roads is dangerous and difficult work. Our county crews are licensed and trained to handle the hazards of extreme weather conditions, out-of-control vehicles on slippery roads, abandoned vehicles, children playing near or in the road, and steep terrain.

Please do not attempt to plow a county road.

Residents or contractors who plow a public road risk significant personal liability if someone is hurt or killed, or if property is damaged. Other jurisdictions such as Pierce and Snohomish counties also do not allow private residents or private contractors to plow public roads.
No. Residents are responsible for clearing snow from driveways.
In 2021-22, we plan to employ private snowplows and drivers who have a contract with King County to assist during very large, countywide winter storms. These seasonal private snowplow drivers would augment county crews and work under the direction of King County snow and ice removal supervisors.
No. It is illegal for anyone other than King County to employ or contract with contractors that are licensed to use any type of equipment that could be used for snow removal or road treatment.

In 2021-22, King County plans to employ private snowplows and drivers who have a contract with King County to assist during very large, countywide winter storms. These seasonal private snowplow drivers would augment county crews and work under the direction of King County snow and ice removal supervisors.
Drivers should always use caution and expect slippery conditions when driving during winter weather.

Ice can form sooner on the decks of bridges and overpasses before it does on the roadway because air can circulate both above and below the surface of the elevated roadway, causing the pavement temperature to drop more rapidly. Ice can also form in shaded areas.
Black ice, also known as “glare ice” or “clear ice,” is a thin coating of glazed ice on the road. Black ice is not actually black. Instead, it is transparent, allowing you to see the asphalt road surface through it. Black ice often occurs along with wet roads, making it hard to see and especially hazardous for driving or walking.
Yes, crews pre-treat county roads with anti-icer when the conditions are right. The surface must be dry and the pavement temperature must be between 20 and 30 degrees Fahrenheit for anti-icer to work. If the road is wet, the anti-icer substance would dilute too fast and fail to work. If the road is too cold, the anti-icer solution won’t stick to the roadway.
King County uses an anti-icer solution called “calcium chloride with boost.” The calcium chloride is salt; “boost” is a solution made of bio-solids such as egg whites and beet juice which helps reduce corrosion on infrastructure.

The calcium chloride (salt) adheres to the surface helping prevent ice from forming. Salt and water can cause rust on metal vehicles and equipment. Boost provides a chemical reaction that prevents rust from forming when the anti-icer solution comes into contact with vehicles and snow-removal gear.
No. Anti-icer is applied to bare, dry roads. De-icer is applied to roads that have compacted snow and ice on the surface. De-icing uses large amounts of chemicals. King County does not use de-icer on our roads.
County crews spread salt, sand or a mix of salt and sand over plowed and unplowed roadways to help make slick surfaces less slippery.

Dry salt is most effective after the snow has accumulated about an inch and the temperature is 20 degrees Fahrenheit or higher. If the temperature is below 20 degrees, crews use a mixture of pre-wetted salt and sand to break up ice and increase traction. Pre-wetted salt and sand sticks to cold, icy surfaces better and jump-starts the ice melting process.

February 11-15, 2021 Snowstorm Recap

See a recap of King County Road Services' work during the February 11-15, 2021 snowstorm. Included are pictures and videos of our crews, in addition to data and information that shows how we supported residents in unincorporated King County by clearing roads during the storm event.

Road Services Division

201 S Jackson Street
M/S: KSC-LS-0313
Seattle, WA 98104

Contact us

Email: Maint.roads@kingcounty.gov

24/7 Road Helpline: 206-477-8100 or 1-800-527-6237

TTY Relay: 711

Twitter: @KCRoads