ten hours below -35C (-31F) last night

ten hours below -35C (-31F) last night, and that's at the warmer thermometer we run, high above the ground near the house. Our lower one, in the nursery hanging on a tree at the bottom of a hill was recording -5C lower, and it stopped working until it warmed above -40.. possibly a hardware limit. So in a low lying area, below -40 for ten hours.. that's as cold as we get here in southern manitoba. zone 3 is defined by extreme low temperatures to -35C (-30F) .. luckily we have a couple ft of snow, and 100 of the fruit trees planted in our new orchard are mostly covered by the snow. our root cellar is well insulated at stayed at -3 last night. the horses do look a little frosty this morning.