Driver door latch and lock failure at extreme cold temperatures. Failed last year could not exit vehicle at Ford dealership. Ford dealership added grease and problem did not occur again for 11 months. Same problem occurred this December. Door latch stays open and will not latch so door has to be held shut by driver while moving down the road. Problem occurred on 4 different days of single digit temperatures during the past 2 years. The ford dealership in Gaylord observed the stuck latch and door not latching. Warning light of door ajar when put into gear and constant warning beeping while driving with an unlatched door.