This blog form Cesar Millan has some good summer tips for keeping your pet safe.
I will only add some tips about moving/shipping/traveling with your pet during the summer:
For flying: when possible, always use a nonstop flight, and aim for early morning or late evening when possible. Pets will have to be tendered to the airline 2-4 hours in advance, depending on the airline and destination – so you want to make sure the pet is in a safe environment during that time period, and not sitting somewhere hot. Make sure the dishes attached to the door are large enough for water, and provide it before handing the pet off.
For Driving: make sure to take water with you, stop in shady spots when you park for a rest stop, and never, ever leave pets in a car. Even with the AC on, the interior of a car can become overwhelming hot quickly.