The city's status of centre of the Fashion industry means that Milan Fashion Weeks are the highpoint of the calendar for many locals and models every year in Late September / Early October, and also at the end of February.
The Fiesta del Naviglio takes place during the first 10 days in June, and should you visit the city at that time, then you will find that there are many parades and small celebrations going on all the time all over the city.
If you know your bebop from your freeform, then the Milan Jazz festival will have you clicking your fingers, and stroking your beard when it takes place during November every year.