If your trees aren't diseased I wouldn't worry about it. A healthy tree doesn't just split down the middle, crack, and fall due to a drought season. There's a whole host of tree-ring evidence out there that says this is true. There are a whole host of tree diseases that will cause a tree to finally die off in adverse weather though... but it has to be sick, and I do mean very sick, first.
PS if your really worried you can call your local arbor society or club and generally they'll come out and give you a free evaluation of both species and heath.

Sometimes even garden clubs in the area will do this service as well as part of their community activism.