People who only support sports teams when they are doing well ie when the "weather is fair." If their team is losing, they don't claim to be a fan, but when their team is winning, they are obnoxious to the highest degree.
Synonyms for fair weather fan
On this page, you will find 30 slang terms related to fair weather fan. Some of the top words include: 40whiner, Raider Hater, pop sharks, 4ever9er, yankees, and 25 more.