Today I looked out at my still green banana trees and other bushes untouched by frost just a few days before the New Year. I thought…this is weird! It is!
Many parts of the Portland Metro area still haven’t seen frost, and when we do finally get a frost, it’ll be the latest ever recorded at PDX. Those records go back to around 1940. So yes, a very mild Fall and early Winter so far. The previous record was December 24th, 1999.
Your next question might be, have we ever gone the ENTIRE winter without frost in Portland. A “San Diego” winter? Yes and no. No, not in the 70+ years at the Portland Airport location. But before 1940 records were kept officially in downtown Portland. It appears that about once every 10 years (on average) there is no frost until at least after the New Year at that location. And at least once we’ve seen no frost the entire winter!
Check out what happened during the Great Depression. There was a normal late-winter frost on February 14th, 1933. But that was the last frost of Winter 1932-33. The following winter (33-34) there was NO frost. I noticed LOTS of 50+ degree days all through December and January. Then, we went all the way through the next Fall and early winter with no frost! Folks were probably thinking the world was falling apart here with a 2nd unprecedented mild winter. Then finally, on January 3rd, 1935, a frost. A little less than 3 weeks later a severe (but short) arctic blast hit. For two days the temperature didn’t climb ABOVE 21 degrees. Wait, there’s more. The 3rd day it jumped back to 51 degrees, and 3 days later, on January 24th, it hit 65…in January! Weird…
Chief Meteorologist Mark Nelsen
Posted by Mark Nelsen 
FOX 12 Weather Blog 