Also found in: Dictionary, Wikipedia.
A person who is supportive of and enthusiastic about a sports team only when that team is performing well. I've been rooting for the home team in their playoff run, but I'll admit I'm just a fair-weather fan.
See also: fan
Someone who remains a friend only when things are going well but abandons others during times of trouble or difficulty. I thought Allison and I had a strong friendship, but I learned she was just another fair-weather friend when she stopped talking to me after my divorce.
Fig. someone who is your friend only when things are pleasant or going well for you. Bill stayed for lunch but he wouldn't help me with the yard work. He's just a fair-weather friend. A fair-weather friend isn't much help in an emergency.
A person who is dependable in good times but is not in times of trouble. For example, You can't rely on Sarah-she's strictly a fair-weather friend. This expression likens fair weather to good times. [Early 1700s]