Waiting for the first UK report which says "an area roughly the size of Wales" is currently on fire in the Northwest. Thought I might help out with the calculations.

Currently the figure for Washington State is 920 sq miles which is 0.114 by the Wales-o-meter . Given that the surface area of Wales is 8016 square miles that is 11.5 in percentage terms . At 275.7 mi² that's more than 3 times the surface area of Ynys Mon/Anglesey ablaze in one state alone!!

UPDATE: In Washington and Oregon at the moment 1,052,388 acres are burning i.e. 1644.36 square miles. This figure omits Montana, Idaho and California all of which are experiencing devastating conflagrations. Given that the surface area of Wales is 8016 this means that an area 20.5% or one fifth the size of Wales is burning in those two States.

( source: https://www.nifc.gov/fireInfo/nfn.htm )

Of course the above figures also omit Alaska where 5,098,829.9 acres or 7966.92 square miles have burned so far this year. An area which is 99% the size of Wales.

(source: http://www.washingtonpost.com/news/energy-environment/ )