The temperature where you are participating in an outdoor activity is a critical factor when choosing waterproof pants. If it's hot, ultra-lightweight pants will serve you best, and zip-off models that convert to shorts might be even better. For cooler days, pants made with heavier fabrics will work better, as they can keep you lower body both warm and dry. For snow skiing, ice fishing, winter camping and other very cold weather outdoor activities, you'll need pants with enough insulation to keep you dry and warm. Choose insulated pants based on how cold it will be when you are outdoors in wintertime. If you are a hardcore, four-season outdoorsman, you're probably going to need several pairs of waterproof pants for different seasonal activities.