FEMA.gov has lots of info, and I came across their Data Visualization page, and found their summary of fire reporting for the state of Washington was interesting:

131,646 fires in Washington State were reported to the National Fire Incident Reporting System (NFIRS) between 2015 & 2019, over 26 thousand fires a year, or some 72/day. 32,566 were from King County, or 6.5K/year: almost 18/day.

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Effective Thursday June 1st at 0800hrs the King County Fire Chief’s Association, King County Fire Marshals Association and the King County Fire Marshal are implementing a STAGE 1 (burn restrictions) Ban.  This ban specifically relates to yard debris/residential burning.

In response to the increased Fuel Energy Release Rates (ERC), decreased 100-hour fuel moisture content (F100), and anticipated warmer weather conditions the King County Fire Chiefs and the King County Fire Marshals, collectively are implementing a STAGE 1 Burn Ban (burn restrictions).  Recreational Fires, Gas/propane appliances, including grills, pellet smokers and charcoal grills are still permitted.

The King County Fire Chiefs, Fire Marshals and local jurisdictions encourage all residents to burn according to their local jurisdictions requirements and maintain a fire safe environment.  If you have any questions, please contact your local Fire Department.

Approved Recreational Burn Requirements: *note some jurisdictions...