...Coolest weather so far this season expected this week...
The coolest weather so far this season is expected through Wednesday before temperatures begin to recover Thursday and Friday.
A chilly air mass will be left behind after precipitation tapers off Tuesday night...leading to chilly overnight night lows Tuesday and Wednesday nights. Wednesday night could be the coldest night so far this season for most valley locations. Outlying valleys are expected to dip into the upper 30s...with more urban areas falling well into the 40s. Some high elevation valleys...and possibly the Upper Hood River Valley...may see their first frost of the season Thursday morning.
Recreationalists hiking or camping...especially in the Cascades... should prepare themselves for the chilly autumn weather early this week. People in the typically colder outlying valleys may want to consider protecting their plants against frost...in case temperatures fall a couple degrees lower than currently expected Wednesday night.