In August, there's Old Home Week at the Charlottetown Driving Park. The main event is the big horse race, but there's also a midway with carnival rides and games, as well as farm animal exhibits. All this happens at the Charlottetown Driving Park. On Friday morning/afternoon before the big race (which is Saturday), there's the Gold Cup and Saucer parade going through Charlottetown. It's a great event for all ages.
Canada Day is on July 1st. On that day and on the few days surrounding it, there are all sorts of events going on, especially down by the waterfront at Peake's Quay. This is known as the Festival of Lights. There's often carnival rides and games, outdoor concerts (Artists/bands such as David Usher, Shay, Rufus Wainwright, Kalan Porter, etc have done Canada Day concerts here), buskers, vendors, and fireworks at night. On July 1st, people walk around the waterfront wearing red and white, and carrying Canadian flags. The Canada Day celebrations in Charlottetown are the biggest ones in Atlantic Canada and are fun for the whole family.
The first-ever jazz festival in Charlottetown was in July 2005, and it lasted for a weekend. Part of Queen Street was closed off because the festival tent was in the middle of the street, and most of the bars in downtown Charlottetown had jazz bands playing there in the evenings. The festival was a big success and will probably be back next year too.