Frost Advisory issued days before possible 90-degree heat around Portland

PORTLAND, Ore. ( KOIN ) — Winter isn’t done with Oregon yet.

A Frost Advisory is issued for much of the Willamette Valley Wednesday morning. This comes just days before highs are expected to climb close to 90 degrees.

Summer heat is in store for much of the Pacific Northwest this week, but not with one final blast of winter-like conditions. Clearing skies late Tuesday night into Wednesday morning will help keep morning lows. Temperatures will likely fall into the 30s for much of the Willamette Valley by Thursday morning. Patchy frost is likely for some in lower lying areas as winds calm and skies clear.

Sensitive plants are at greatest risk to frost damage Wednesday morning. Action should be taken before sunset Tuesday to bring potted plants indoors and cover fresh vegetation that can’t be brought indoors overnight.

This late season frost threat comes well after the average final freeze of April 18, but frost has been recorded as late as May 23 in Portland. This late season cold snap is followed by a major warming trend in western Oregon and Washington.

Afternoon temperatures will rebound into close to 70 degrees by Wednesday afternoon as sunnier skies return to the greater Portland, Vancouver metro area. That’s just the start of this week’s warming trend.

Summer-like heat is expected by the end of the week where records are being threatened. This round of weather whiplash might come as a surprise to unsuspecting residents of western Oregon and Washington.

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