Skip to main content

Winter weather: Snow and ice in unincorporated King County

Winter Weather Response Map

Winter Weather Response Map.

When it snows, use the Winter Weather Response Map to find plowed and sanded roads in unincorporated King County.

24/7 Road Helpline

24/7 Road Helpline

Call us for help with snow and ice on King County unincorporated area roads at 206-477-8100 or 1-800-527-6237 — 24 hours a day

Check your snow route

Will your route be clear this winter?

Road Services plows and applies snow-melting treatment to 583 miles of designated snow and ice routes. During snowy weather, our main goals are to keep the major roads in Unincorporated King County open for travel, and to ensure the safety of travelers and our dedicated crews. Our snow and ice routes are categorized by number and are plowed and salted in priority order.   

Priority plow routes – Where we plow first 

We prioritize clearing snow from the most heavily traveled roads:

  • Major thoroughfares and arterials
  • Transit routes
  • Roads that serve densely populated areas or connect communities
  • Life-safety routes, roads that lead to hospitals, fire stations and other emergency services  

These routes are shown as Category 1 and Category 2 on the Snow Routes Map (2MB). It could take up to three days or more to plow and treat Categories 1 and 2, depending on how much snow we get or how icy the roads are. 

Other plow routes

After the Category 1 and Category 2 roads are clear, we move on to plow snow and apply salt to the remaining snow and ice routes along less-traveled roads and in neighborhoods (categories 2, 3, 4 and 5).

If you do not live on a Category 1 or 2 snow and ice route, be prepared for the possibility that you may need to stay home and avoid driving for up to several days during a major, countywide winter storm.

This is because snow may accumulate faster than our plows can keep up with. Crews must continue to re-plow Category 1 routes until they are all clear before moving on to Category 2 routes.

Emergency road plowing

If you have an urgent or life-threatening emergency and your road is not plowed, call 9-1-1. We collaborate with first responders to clear roads outside of our usual snow routes when instructed by 9-1-1.

Map of 2023-24 snow routes (2MB)

Be prepared!

Resources for emergency preparedness  

The National Highway Traffic Safety Administration has a helpful list of winter weather driving tips found here. Washington State Department of Transportation has provided a couple of great documents – found here – to print or save to use during the winter months. – to print or save to use during the winter months. 

Winter weather frequently asked questions

There are 1500 miles of road in Unincorporated King County. We make the best use of our limited resources by focusing on plowing one-third, 583 miles of this road network.   
Road Services works together with public safety officials to decide which roads are included in each snow and ice route. The selection process primarily considers the role each road plays – such as access to hospitals, connecting communities, facilitating bus routes, or serving as access points to highways. The snow and ice routes are categorized from 1 to 5, with top priority given to plowing the roads that are most heavily relied upon by the largest number of people as well as those used by emergency responders.  
Category 1:
  • High-volume arterial roads that provide regional connections between communities and main highways
  • Lifeline emergency routes, routes to hospitals and other emergency services
  • Transit snow routes
At times, snow may accumulate faster than our plows can keep up with. Crews will continue to re-plow Category 1 routes until they are all clear before moving on to Category 2 routes.

Category 2:
  • Main thoroughfares and roads that lead to densely populated areas and state highways
  • Minor collector roads that serve densely populated areas
Some Category 2 routes may be delayed or not plowed and treated until all Category 1 routes are fully clear.

Category 3:
  • Main roads that connect towns and large subdivisions with cities
  • Roads connecting Category 1 and Category 2 routes.
Categories 4 and 5:
  • Residential roads in lower and upper elevations that connect neighborhoods to each other.
In most cases, communities should not expect roads other than designated snow routes to be plowed and sanded in any type of storm.

We do our best to clear designated snow and ice routes in priority order. Sometimes unforeseen issues arise that slow down our progress. Some examples are:  

  • Snow accumulates faster than our plows can keep up with and we need to continue to re-plow Category 1 routes until they are clear before moving on.  
  • The need to redirect crews off a snowplowing route to clear a fallen tree from a different road.  
  • Emergency responders ask us to clear other areas so that fire trucks and ambulances can respond to a 9-1-1 incident.  
  • Snow plowing may be delayed due to equipment breakdowns. 


During an active winter storm, we cannot fulfill requests to plow roads within our designated snow and ice routes. At times, it may be possible to honor a request once the storm has passed. It depends on how severe the storm is.  

In most cases, communities should not expect roads other than designated snow and ice routes to be plowed and treated 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. 

It could take several days for crews to clear and apply snow-melting mixture on all 583 miles of designated snow and ice routes. You can check the Winter Weather Response Map (*temporarily offline) to see where our plows have recently plowed or cleared snow from the road. The information on the map is posted approximately 15 minutes after the road has been plowed. The time delay helps prevent drivers from tailgating our snowplows. Please stay a safe distance away from our snowplows, trucks, and equipment.   

Please note: Snow may accumulate faster than our plows can keep up with. Crews will continue to re-plow Category 1 routes until they are all clear before moving on to Category 2 routes. 

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 first responders and the Office of Emergency Management.

We prioritize plowing categories 1 and 2 snow and ice routes before moving on to categories 3, 4, and 5. Occasionally, due to weather challenges, steep hills, or obstacles, our snowplows may need to take a different route, like a non-county road or a county road on a category 3, 4, or 5 snow and ice route. In such cases, the snowplow usually must clear the snow from the roads it needs to use to reach the category 1 or category 2 snow route. 
This also happens when first responders request for us to plow or treat a road for emergency response.  

King County employs year-round licensed and trained road maintenance crews that are experienced at operating snow and ice removal equipment. Crew members actively travel unincorporated King County roadways around the clock to monitor and respond to winter weather such as ice and snow, flooding, downed utility wires and downed trees. 

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. 

King County uses private contractors (when available) to assist during very large, countywide winter storms. These private contractors 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.

No. Residents are responsible for clearing snow from driveways.

During a countywide or localized snow and ice event, our resources are dedicated to safety and clearing our snow and ice routes. King County Road Services is not responsible for clearing parking lots, driveways, or sidewalks for residences or places of business. We encourage residents to help us by helping one another. If you live in a residential development with a Homeowners Association, the details of how your streets and sidewalks are maintained is likely outlined on the front sheet of the subdivision approval document.

Please note we prioritize the designated snow routes for treatment with our limited resources.

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.

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 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.

We evaluate the routes as needed with public safety officials to determine the routes based on the category criteria. This evaluation determines if the road function or conditions have changed (adding lanes, increasing incline or decline) or if other information indicates there is a need for recategorization. Examples of why a road may be recategorized are: 

  • The addition of a large subdivision increasing road traffic.
  • The road becomes a route for first responders or emergency services. 
  • Addition of public transit stops and routes.  
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.

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.

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 calcium chloride (anti-icer) when conditions allow. This anti-icer is a type of salt that works well in very cold, dry conditions. The anti-icer adheres to the surface helping prevent ice from forming. 

Anti-icer is different from de-icer. 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.

County crews spread salt, and occasionally a mixture 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.

We use a salt/sand mixture occasionally. Many local and state transportation agencies use a salt first approach because dissolves snow quickly, melts ice fast, and prevents ice from forming. Less snow and ice on the road is safer and helps prevent collisions.


  • Life-Medical Emergency call 9-1-1.  
  • Roads blocked with trees, utility wires, or fallen ‘Stop’ signs, call our 24/7 Helpline at 206-477-8100.  
  • Non-emergencies you may email  

Preparing for snow and ice videos

Roads and flooding

Flooding can occur after a heavy snowfall melts. Learn about flooding in unincorporated King County and our response.