I would be less concerned with heat than major shifts in humidity. It is when the humidity drops that wood can do twists and turns, and can split along the grain. The more figured the grain the more it twists. Think of a wood kiln and the dry heat. Not the type of condition you'll find on Long Island where relative humidity is on the high side of the scale.
You'll not want to keep your guitar in the direct sunlight as that will affect the finish but I wouldn't be concerned with 90 degree heat.
As far as laminate goes.. plywood is a form of laminate and the cross grain layered manufacturing process is done to give it strength and lack of suseptability to the elements.
