The Montreal Jazz Festival runs from late June through July. I don't know the web address offhand, but if you do a search for "Montreal Jazz Festival", I'm sure it will appear. We went last year and it was fabulous! Jazz acts play in different venues (clubs, bars, outdoors around the city) from afternoon until late at night. The main location of the festival is around the Westin Hotel. The streets are blocked off and different bands play outdoors. Most outdoor acts are free, otherwise there are various admission charges. Have fun on your trip! Montreal is a great city! (as for chow, try to avoid Crescent Street and Peel Streets, they are both very touristy, with overpriced mediocre restaurants. Most late night activities will be on or around the Rue St Laurent, where there are lots of nightclubs, restaurants, etc.)
1254 Mackay [just below St Catherine O]
This place is really good, and intimate. It's a small jazz bar/club/restaurant. It's got decent food.
l'Air du Temps Jazz
191 St Paul O
Never been, but heard it's good.
Biddle Jazz & Ribs
I went there once. Really good jazz, good ambience...but crowded & expen$ive.
Pick up/look online at:
Check out whatever other festivals are going on in Montreal, too...