I wouldn't doubt it.  I know bet its bad to leave them in any extreme temperature hot or cold.  I'm looking forward to a response from an expert.

I would say extreme temperatures, hot or cold, can affect the epoxy. Why aren't they next your bed?  ;)

RYAN,

REMEMBER I LIVE IN KINGWOOD,TEXAS AND ANYTHING BELOW 35 IS EXTREMELY COLD.

IN ANSWER TO YOUR SECOND PART,,,,,,,,,,,,,,,,,,,,,,,,,,,ARE YOU MARRIED?  LOL,LOL

Haha!

Mine are currently in the guest bedroom because I am married.....  ;)

Dogloski,

I live in The Woodlands, TX and it is freakin cold right now. You gotta find a nice comfy place inside for your sticks or they may get upset with you. Your wife has to accept your other love and explain to her it's not another woman and that your clubs will get upset if they are not treated right. Lol!......................I keep mine in my living room whether it's cold or hot, that way I know they will not betray me on the course.

John

DEAR JOHN,,,,,OH,OH,,,,,,,,,,,,,,,I'D BETTER BE CAREFUL OR I'LL BE GETTING ONE OF THESE DEAR JOHN LETTERS,,,,,,,LOL,LOL

It is not wise to leave your clubs in any extreme temperature be it hot or cold.  I think the biggest error is leaving them in a hot car trunk.  The fluctuating temps drive moisture into the irons and will rust them from the inside out.

I keep my clubs in the guest room as well.  It's a good way to protect my investment.

My golf room becomes a guest bedroom.    First things first.

Deno

I have a guest bedroom for my wife, my clubs don't leave my side, come on now fellas :)

Good thing I know she does not read this site.  haha

When my Fiance complains about my clubs in our guest room I just open the closet.  When all her shoes fall out it takes up way more space than my sticks.  Enough said.

I tend to leave them in the trunk almost year round.  I know......but I never know when I might play so I always try to be ready.  Now you guys got me worried!  Thanks

I am an engineer and although not a materials expert, have a lot of experience.  The only thing that freezes at 32 is water.  I don't believe there is significant water in the shaft or the epoxy.  I know the temperatures won't affect the metal portions.  

If it seems right to you to bring them in, then do so.  If you enjoy leaving them in the trunk or garage, I wouldn't worry about it. --jerry

PS  Same for balls. I'd say no problem.