How long does smokeless gun powder last?

Reading a recent post made me think. I don't store guns or ammo in the car but do have a fair amount of loading supplies in the house. The house stays at a pretty fair temp, maybe 70 to 80 (90 at tops) F. I'm wondering how long my cans of powder will last? Humidity does change since I live in Western WA but not too bad. I've had cans of powder for over 5 years now and am thinking about loading up some rounds with them. Any thoughts?

Cherokee

Should be ok. The cans are pretty good at keeping moisture out.

If when you open the can, the powder is clumping, it got moisture in it. At that point.... make really nifty firestarters that will add a lack of eyebrows to your problems if you need them in a real emergency?

Should be fine. I am still loading some double base powder that I bought 25+ years ago; it has traveled from Georgia to Alaska and coast to coast in the lower 48, coming to rest here in the MidWest where I am slowly shooting it up. According to my records It chronographs the same as it did new. I have a bit of single base that is older than that and it looks and smells fine. I have some WWII ammo that shoots fine (but it does have corrosive primer compound, fwiw). I've even fired WWI 45ACP and 9mm and it shot just peachy (the 9mm was a little hot, actually, but burned clean as a whistle. Just how they loaded it back then). Your 5 year old powder should be fine.

And smokeless powder has no affinity for water afaik - it should not appreciably absorb any moisture from the air. (Black powder can, of course - again, I have some DuPont FFF that is really old, but it shoots fine in a cap and ball revolver of mine - apparently the original cans do a good job. I'm down to my last 1/2 can of the DuPont stuff...)

Great info. Thanks. I really appreciate it.

Cherokee