are all die hard movies set at christmas

Not necessarily, although many of the movies in the "Die Hard" franchise have a Christmas theme or take place during the holiday season. The original movie "Die Hard" takes place on Christmas Eve, and the sequel "Die Hard 2" takes place during the holidays. However, the third movie in the series, "Die Hard with a Vengeance," takes place in the summer, and the fourth movie, "Live Free or Die Hard," takes place during the Fourth of July. So, while the first two movies have a strong Christmas theme, the franchise as a whole is not exclusively set at Christmas.