There are many factors that affect our weather here in the NW as others have already mentioned. We have two major mountain ranges east and west of us, our latitude and the Pacific Ocean.
The average temperature of the ocean is about 50 degrees which influences our temperature, so it doesn’t get too cold in the winter or too hot in the summer. Systems might come up from Hawaii, but rarely do we get cold blasts from Canada. These jet streams from Canada bypass us and head east.
We do have short periods, usually no more than a week long that temperatures are in the 10’s. So far this winter we have gotten into the 10’s twice, in early November and December. Normally spring starts around March, but very rarely do can see snow in the first week in April. We get a foot of snow every few years that only lasts a few days.
There is very little die back of the Desert King, a few tips here and there. I do protect my young plants and put them in the shop for the winter and not in the greenhouse. The greenhouse gets warm on sunny days.