I spent several years in my teens using my dad's Heathkit SB-102 rig out in
the garage in Fort Worth. Yes, it does get hot around here during the
summer, make no mistake about it. I'm a night owl by nature, and I can't
count how many times I worked DX until the sun came up.

Pros and Cons:

* Keep the garage door open, and open the back door as well to let air flow
through. Cheap, but effective only during the day. At night, june bugs and
other critters are attracted by the interior lights and will make life
miserable for you. (I'll never forget one on-air conversation when a june
bug flew right down my shirt. "WHAAAAUUUGH!!!") These days, unfortunately,
it's not wise to leave your garage door open unattended because some *@#$
might come in and steal all of your power tools. (Bitter experience.) Or
worse.

* Our garage had a VERY good wall-mounted air conditioner. It worked
beautifully, even during the long, crushingly hot summer of 1980. In fact,
it saved my parents' bacon when the house's main A/C unit failed and it took
a couple of days to get it fixed. Mom & Dad just backed the car out of the
garage, plopped down a mattress, turned on the wall-mounted A/C, and slept
in cool comfort. [I'm sure Dad woke up each morning wondering, "What did
she do to the bedroom now?"] Nice backup to have. I could work 40 meters
all night long without worrying about the heat or the bugs.

* The garage also served as a nice workshop, complete with parts cabinets,
two workbenches, and lots of tools. Easy to try out new RF circuits
quickly.

I like the tornado-shelter idea. It's smaller and easier to keep cool.
Also easier to secure valuable equipiment.