Oldjarhead,
From one old jar head to another, you're going to get all sorts of replies, but as I've gotten older I've decided that holsters are over-rated. And everyone knows what are inside fanny packs these days.
There are other options that work better for me, with less discomfort. Primarily they involve garments that are designed to carry pistols in.
Here are some examples:
http://concealmentholsters.com/pgro...+Items/29_Concealment+T-Shirt+-+V-Neck+Style/
The first is from Under Tech, but Kramer and others also offer similar products. While lots of guys just "go Hawaiian", there are shirts that are designed to work well over concealment T's, like the 511 covert shirts:
http://www.911tacticaldirect.com/511-shirt-covert-casual-71170.html
Finally, I have owned three of the Coronado vests for travel, and they work great - and I was in and around Albuquerque, NM - some places are surely hotter, but summers in NM can be reasonably toasty:
http://www.coronadoleather.com/browse.aspx?c=7&n=707982
The common denominator to all these products is that you're limited to guns that are basically pocket-sized, low-profile, thin, and easily concealed. Trying to put a Colt Commander in the pocket of a leather vest looks like you're trying to conceal a large ignuana.
That said, in hot weather I'd rather tuck a pistol in a pocket somewhere, (in a pocket holster,) than use an IWB holster or some other rig. It's just more comfortable...assuming that you don't feel "under-gunned" with a pocket pistol!
Semper Fi,
Doc