I live in New Brunswick and since the border to NS is literally 15 minutes away from me, here's a few tips/ideas.
Bring bug repellant. Bugs are bad this year, although if July warms up and dries up it might get less so later.
Halifax is normally cooler as it's along the coast, but still bring warm weather stuff like shorts and t-shirts. You'll see lots of people in both, sandals, flip flops and so on around.
It depends on where you camp out for what to expect. Shore and woods camping differs. With the shore you get the cool breeze, the water and waves but you'll also have a greater chance for fog. If you're woods camping, bugs will be the problem. It can get hot, yes, but humidity is the worst comparatively. Expect to feel "sticky" at least once during your trip.
Other than that, Halifax is a great area and if you can, check out the waterfront. The Jazz Festival is in July, as is the Tall Ships, just to name two big events in July (outside the concerts and, depending when you go depends on the band). Try
195 events - Eventful for ideas depending on the dates you plan to be in the area.
Hope you have a good time.