Frost/Freeze in Yakima Valley, Washington

The ASOS KYKM recorded temperatures at or below 32 degrees for approximately 4 hours ending at 0655 PDT. The AWOS K1S5 recorded temperatures at or below 32 degrees for approximately 3 hours ending at 0415 PDT. The mesonet station W7YKM-3 Tieton recorded temperatures at or below 32 degrees for approximately 2 hours ending at 0220 PDT. The RAWS station YTCW1 recorded temperatures at or below 32 degrees for approximately 8 hours ending at 0807 PDT.

Increasing northerly flow reinforced by a cold arctic airmass behind a shortwave trough passage starting October 26th lead to temperatures region-wide dropping well below normal. Overnight temperatures across the lower elevations in the intermountain Pacific Northwest were able to cool well below freezing across the region for much of the overnight period. This lead to all lower elevation zones experiencing their end of season freeze by the morning of October 28th.