At both nurseries we can be cold. If you wander out on a winter day dress like an Eskimo, with shorts under the layers. Our temperature in the last week have ranged from the high 80's to 8.
Native plants can be very tolerant of our temperature swings and we usually do not take big loses until we get below 0F. Yes we do sometimes get below 0.
Log on and share your low temperatures. Right at the moment Whitehorse in the Yukon is about the same as us.