From the PDX National Weather Service:
Another round of hot weather expected later this week. Triple digit heat may make a comeback across portions of SW Washington and NW Oregon. A quick warming trend will begin Wednesday as offshore flow strengthens across the region. Temperatures across the inland valleys will likely surge into the 90's on Wednesday, possibly reaching 100 degrees Thursday and Friday. The offshore flow will initially result in a dry heat Wednesday and Thursday, but humidity is expected to increase Friday making it more uncomfortable.
Also making things more uncomfortable will be a large surge of people saying inane things like "Hot enough for you?" and a 75% increase in Facebook status updates mentioning heat.