Typically temperatures in February are some where between -15 & -40 degrees Celsius. The extreme temperatures will usually only last a day or two but have been know to last longer. On average I would expect most days to be in the -20 degree range. So long as you have the right clothing and eat well, you will be fine. I will constantly checking in with you, to ensure that you are warm and have plenty of tricks which will help you warm up.
In Autumn, it can drop a few degrees below freezing over night and is quite mild during the day. Somewhere between 5 & 12 degrees Celsius is the norm.