Household door mats for outdoor use are a vital tool in keeping dirt and grime out of your house. Stopping dirt, moisture and grime at the door step is so much easier than cleaning it out of the house.
Door mats used outdoors typically have the function of removing the heavy dirt and grime off of the bottom of your shoes before you bring it into your home. They usually do very little to dry your feet so used in conjunction with a quality indoor mat will yield much better overall results.
In addition all outdoor entrance mats will usually perform much better if they are under some kind of overhang or covering vs. a door mat sitting out in the open especially in areas where snow and ice occur.