There are a few interesting events in Montpellier

Hivernales. It's a Christmas market, usually held in Place de la Comedie/Champ de Mars every day during the month of December. There are stands where you can buy nice ideas for Christmas or street food. Some animations are held during weekends

Estivales. Held during summer (July -August) Friday form 7pm to 12am. Same place of Estivales, similar idea but this time vine is the protagonist. You can buy a ticket for 3 wine samplings (price increased over the years, from 3€ a few years ago to 5 or 6 recently). They give you a glass and three tickets, then you can move between the different producers and taste their wine. If you like it you can also buy a bottle. Quality really depends on the producers, some are really good (Muscat de Lunel for example) others are really nothing special. You can try your chance or ask to the producer some details. In the same location there are also food vendors, so it's nice to have a picnic and eat on the grass. Also some other vendors, among others painters, jewelry and clothes. It's crowded but people are there to have fun and they are usually very friendly (wine helps). Close to the Corum end there are concerts that varies from time to time (salsa, rock, the kind of music good to dance). On the other side it's more quiet, better to talk. At midnight the magic ends and a crowd of cops push you away to avoid late night noises.

Fete des vignes. End of November, one weekend Fri - Sun. The system is similar to Estivales, but this time it's for wine tasting (and buying), not for party. You receive 3 coupons for wine tasting and a glass for 2€. This time they really give you a little wine, to taste. If you like you buy the bottle. Part of the festival is in Champ de Mars (near Place de la Comedie), but part is held at Domain d'Ô. Sunday wine maker open their domains and let curious and wine lovers visit their cellars and taste their newest production. In this case you need a car

ZAT. Zone Artistique Temporaire is a street festival that takes place a few times a year (2 to 4), each time in a different neighborhood and with a different theme. Artist take possession of the places and this is really the best way to discover some of the hidden gems of this city. Performances are of all kinds: artistic installations, story tellers, painters, musicians... A couple of years ago (2014) they did wonderful fairy installation on the theme "fire". This performances are not regular and you need to keep an eye on Montpellier's calendar to check if there is something when you visit the city.

Festival du Domain d'Ô. Art festival, music, theater, dance. Host in summer, at Domain d'Ô. This is really a good occasion to watch to some good theater, often modern and fun outdoor. Being en plein air is really what gives to this festival its charm. 

FISE. This is the International Festival Extreme Sport held in Montpellier beginning of May. If you like crazy acrobatics on BMX, Roller, Skate, music and a lot of people this is the place for you. The competitions can be watch for free and you'll have the best of the best performers.

Other festival of lower interest are 

  • Arabesque. Festival about the Arab culture
  • La Comedie du livre. End of May. Book takes control of Place de la Comedie. It's pretty small though compared to other book fairs
  • France Open. For tennis fans Montpellier host one of the stops of tennis cup "Open de France"
  • Montpellier marathon. March. This is not New York Marathon but if you like running till the exhaustion you should be here
  • Boutographies. Small photography Festival, in May.