Weather in northern Minnesota can be extremely temperamental. A day that starts out gorgeous can turn drab, cold and rainy in a heartbeat, and vice versa. Check the weather reports for the location where you will be staying, and pack accordingly. Northern Minnesota weather is also notorious for being very cold, so pack warm clothes. Good ideas for weather-appropriate clothing and gear are: waterproof jackets, sweaters or sweatshirts, long underwear and sturdy, waterproof hiking boots.
Northern Minnesota offers facilities for most types of traditional camping, from rental cabins to RV parks to basic campgrounds. Some northern Minnesota state park campgrounds, like the one located in Tettegouche State Park, are open year-round.
Minnesota law prohibits the introduction of out-of-state firewood and campfires are banned completely in any state forest. It is also a good idea to always leave your campsite as you found it---neat and free of refuse.