I would like to create a place for ammo storage in my attached garage. We are in the high southwest desert. Temperatures in the garage range from a high of 100 degrees in the summer to a low of about 40 degrees in the winter. Humidity is always quite low, sometimes single digits in the summer.
Do you think these conditions are acceptable for long range ammo storage? By long range I mean up to three years. Ammo is a mix of my carefully prepared handloads, and some factory stuff.

I'd be leery of 100 degree heat. How much ammo do you have? Find a place in your house to store it.

I keep mine in ammo cans in the bottom of my bedroom closet , mostly . I do store some in the garage but have noticed that anything kept long term tends to get a bit green due to climate fluctuations . My garage is not insulated and can be at 100 degrees in the summer and down into the teens during winter . It also tends to be a bit humid .

Eddie

__________________
Grumpy Old Man With a Gun

When I lived in northern NV, I kept all my ammo in the garage - all went bang. Moved a lot of it to Florida. Metallic I can mange to store inside, but not shotgun. Some of that stuff is now going on 20+ years old, the last 14 in the heat and humidity - all goes bang

It may still go bang but personally i'd be worried about the pressures. It's almost been a universal axiom the high heat is the greatest enemy of ammunition. I live in Arizona and all my ammo is stored in cool, dry locations for this reason.
Jim

I keep making room for my shooting hobby in the closet, by slowly donating my husband's "excess" clothing to charity.

I would try to look for alternative locations over a garage in the south/sw. When we were in SC, seemed our garage temps could hit higher than what was outside if the sun pounded on the door/glass just right; esp if i stored items higher up in the garage. I'd wonder if garage temps above what is outdoors in summer in AZ could be a possibility depending on direction the garage faces, etc.

But what do i know, i'm sure that for decades up here my in-laws have stored stuff out in garages/sheds not attached; and heaven knows the temps and humidity up here can swing wildly lol

I'd gladly look the other way if the wife wanted to donate some of my stuff if it allowed me more space for my growing hobby lol

I think you just gave me an idea.
Will start with my wife's shoes. She will never even know.

NV was more of a cooler than hotter climate - summer temps in August might hit close to 100, but evenings were cool and rest of the year could be very cool to downright cold. Military stores ammo is worse conditions than my garage.

I still have room in my gun cabinet, but it's getting close to full.

Time to have a good closet cleaning....anything that hasn't been used in the last 10 years gets donated.....it's amazing how much room for ammo you will have.
Yard sales are excellent ways to get rid of "stuff".... I was amazed that people would pay money for things I would have thrown in the trash....mark it vintage and stand back !
I sold tie-died T shirts and bell bottomed blue jeans all the stuff from college in the early 70's...went like hot cakes!

I store my ammo in regular ole military style ammo cans out in my work shed that I reload in. I live in Texas and it hits 100 degrees + all the time with ton of humidity to boot. In 45 years of doing so, never had a problem. I’ve even shot some of that 45 year old ammo too.

That is just like I do down to the time frame of 45 years and the shed out back that holds my extra stash. I do use Zcorr bags in the ammo cans keeps the rounds nice and shiny for years.

The powder and primer will be ok, though 100 is a little warm. It's the brass that will probably be affected first.

The only problem would be how often the temp. falls below the dew point. Maybe throw some desiccant packs in there.

I'd keep some out there, but check it every coupla months or so. If no change great. If some change, ok. If it starts turning green, shoot it up quick.

I'm in an awful climate for corrosion. It gets cold and hot here and the humidity is high. So every time it crosses the dew point, my ammo gets doused if it's out there. Storage in my garage would be short-term only.

__________________
"He was kinda funny lookin'"

I moved from the damp Seattle area to the hot/dry Prescott, AZ area and all of my ammo is stashed in the garage. Temps ranged as you can imagine and we get over 100 at times here on occasion.
All my ammo including factory and reloads have performed very well with no issues. And all my reloading components are doing just fine. Of course the most important thing in my opinion is keeping it all dry.

__________________
Tom Graham SWCA #2303

I have a bunch of 6.5x55 ammo that was made in 1918. Unknown storage conditions but expect they were not that good. The stuff looks pretty nasty. But it all works just fine and after a few hours in the polisher the empty brass looks the same as the brand new stuff.

In short I would say NO! COOL & DRY is what they deem the best way to store long term. 100ºF is NOT cool. I'd figure out a place within the house that is presumably climate controlled.

I live in inland S California so it is hot out here also. You will find that the temp of your garage is generally 20 or more degrees cooler at the floor...heat rises remember. I put a cheap gun cabinet on its back directly on the slab floor. I put a thermometer inside to see the temps. I found the temp even during weeks when the temp was 105 or so never exceeded 80 and was usually in the high 70's . So I leave ammo cans inside the cabinet and spot check the temp periodically. In the winter when it is in the 40's the temp is in the upper 60's and as I said above on very hot (110) days it runs in the 70's and 80 once or twice a summer. Just buy a thermometer and place it at ground level and you will see.

We worry too much about storage conditions. I have a couple of cases of M2 Ball headstamped FA50 that remains shiny and shoots just fine. It's experimental non-corrosive and probably stored under conditions that would make us cringe. It still has the factory lead seals and that great smell when opened.

I just moved to central Arizona from the "low hot" desert of Phoenix. I just purchased a large Rubbermaid storage cabinet for my ammo. I have no problem keeping my ammo and reloading components in the garage. I once kept a case of PMC 9mm target ammo and a case of Malaysian 5.56 circa 1980 in my garage in Phoenix (130 degrees) for over 10 years. I think there was a pound of #5 in there also. When I finally did break them out, they all functioned and fired perfectly. Maybe there's a lesson yet to be learned for me. We'll see. I'm sure that the low humidity of the Southwest helps.