Yesterday, Seattle-Tacoma Airport got to 95F, breaking the previous daily record, while Willamette Valley locations hit the century mark (see Friday max temps below). Ironically, eastern Washington cooled substantially from Thursday due to a surge of cooler air from the north (and which was MUCH stronger over Montana).
Temperatures should be similar over the western WA and Oregon interiors today, but a push of marine air is expected tomorrow west of the Cascade crest as a significant trough of low pressure moves through.
The coast should be cooler today, as the offshore flow weakens and the thermal trough moves inland. The visible satellite imagery this morning shows a sign of this....a tongue of stratus hugging the coast. You will also notice the plumes of smoke from a few fires over the Olympics and Cascades.
Temperatures above Seattle are just as warm this morning as yesterday and the low level northerly winds (which cool) are weaker (as shown by the time-height cross sections from the profiler at Seattle Sand Point below).
The UW WRF high resolution model surface temperature forecast for 5 PM (below) shows very warm temperates again over the Willamette Valley and southwest Washington (96-100F), with lower 90s extended north to the southern Puget Sound. Cooler along the coast.
Sunday will bring a major push of marine air and temperatures dropping by 10-20F. The latest numerical forecasts suggest an even stronger ridge of high pressure building mid to late week, with temperatures climbing again into the 80s and 90s. (see sample below). The wildfire threat is increasing, as the above normal heat dries the surface fuels.