It get VERY hot here in the summer and its not so much the heat that is unbearable,its the damp atmosphere (I live on a little Island).
It gets so damp sometimes that everything seems wet (curtains,bedding,couch etc etc) so we have to leave our AC on all day to dry out the air and keep the house cool.
When we go out,we dont leave the cold air on full,but the de-humidifier stays on to make Lady and Jessies day more comfortable.Without it I think it would be unbearable for them

Also,we only walk them at night in the summer because the heat is way to much during the day.
Water is a must,and if its got a few ice cubes in it then all the better