If you live in a temperate zone such as the west coast or the south, you may not be too concerned with snow and temperature extremes. For others, weather may be a major consideration. Will it hold up under extremes? How well does the door seal from hot or cool temperatures and wind?

Most doors are not well suited to high extremes and hard plastic may become brittle at sub-freezing conditions or flaps may get stiff and fail to seal properly. At the other end, if your door is in direct sun in 110+ degree temperatures, plastic could deform. Aluminum doors are best for these kinds of extreme conditions, but they are also really poor insulators, so it's not going to help your heating/cooling bill!

If you're subject to harsh weather conditions, you may not want to let your pet out on their own either, so a door that can be blocked off may be the best solution.