I do a lot of flying in temps between 20 and 40 degees F using Nicads and Lipos. If you charge and warm the batteries up prior to putting them in the plane you will notice no loss of time or power. If you don't keep them warm prior to use you will notice more loss of power than loss of flight time, but you will lose both. After charging, I keep the batteries I am going to fly in my pockets close to my body so they will stay warm, or I leave them over the defrost vent in my truck. Sometimes I stay in the truck and stick my antenna out the window! I suspect judging from were you live that you might be wanting to fly in temps much colder than 20 degrees F. You might have to check with some clubs "local" to you or find out by trial and error what you can get away with!