In Phoenix his cloths will be as dry as toast when he gets to work as will he be. They will both be covered in salt though. If I was doing a 25 mile ride out there I would plan on 4 bottles of water on the bike both ways in the summer.

Last time I was out there it was February 2011 and the noon temp was 102 we played golf and I put down 9 bottles of water in 18 holes and never was the least bit damp and never went to the bathroom all day. Felt very healthy and nothing like 102 on the east coast. On the other hand without the H2O I would have been sick all afternoon. Staying hydrated out there is something you really have to work at. I would suggest the cool down couple miles and then an outdoor cool down in the dry heat 10 or 15 minutes in shade before hitting the air con. Spruce up as mentioned above and he should be fine. Just get the salt off the skin it’s hard to believe you can sweat out that much water and never get damp but that’s Phoenix AZ.