National Oceanic and Atmospheric Administration (NOAA) has posted The Climate Explorer, an interactive map and graph showing average temperature predictions for every county in the nation for each decade through the rest of this millenium.
The predictions for San Juan County, WA are shown in this graph.
Use The Climate Explorer to learn how climate conditions in the United States are projected to change over the coming decades. This information—derived from global climate models—is available for counties and county-equivalents for all 50 states and U.S. territories.
The Climate Explorer is posted in HEAT.gov, the web portal for the National Integrated Heat Health Information System (NIHHIS). Heat related illnesses and death are largely preventable with proper planning, education, and action. Heat.gov serves as the premier source of heat and health information for the nation to reduce the health, economic, and infrastructural impacts of extreme heat.