Fondue is a winter dish. If you have a hankering for some melted cheese in the summer, eat raclette instead (raclette cheese melted and scraped onto baby potatoes and cornichons).
Fondue is also a social dish, and it should be shared with as many friends and family as can sit around the table and reach into the pot.
Of course, rules are made for being broken... I usually jump at the chance to eat it whenever the occasion arises, even in the summer time.