>>150327108
The difference is quite large. In a place like Phoenix, you can mist yourself with water to help keep cool. In places like Houston, at best it might make you stink a bit less from all the sweat. The danger in Phoenix is that you might not realize how overheated you're becoming until it's too late. For sporting events, that's typically a minor annoyance since you can go find some shade and there's medical personnel on hand to assist if you do get overwhelmed. Go out for a hike unprepared and you might not be able to get back to your car for water and cooling.