I need to store my desktop PC somewhere during winter break. I found a place that rents out sheds for cheap. However there is no temperature control, so the shed will be the temperature of the environment. They are waterproof. Is it safe to store my computer outside like this? This is near Houston.
First, do a backup. But do not store it with the computer.
Get yourself a large, plastic storage bin and place everything inside. Throw in some desiccant packs and run a bead of silicone sealant around the top of the bin before you close it for the last time.
It will be air tight so you don't have to worry about condensation when the temperature changes. It will be virtually critter proof (ants, spiders, hornets, rats eating cables, etc). If the storage facility experiences weather damage or flooding, you're covered.
When you retrieve your computer, let it come to room temperature before you open the bin. Clean it out, check the seating of cards, memory, etc.
It should be fine.
See the answers to this question on starting a cold computer.
Basically, as long as the computer is kept dry and you let it warm up to room temperature before using again you should be OK.
I should add that wrapping it in some sort of insulation might be a good idea. Extreme cold could affect some of the components even when not powered. But you shouldn't need to go overboard on the insulation, a blanket, old duvet or sleeping bag should suffice.
But then again I don't know how cold it gets in Houston in winter.
Electronics normally have both operating and non-operating temperature requirements. You will want to look at the non-operating temperature requirements. Since it seems alot of electronics are fine up to at least 100 degree F and below freezing, then you should be fine here I think. Humidity might be another problem, potentially causing corrosion. You could seal it in a package as best you can and throw a bunch of those silicone packets in it. It is important you put it in as small a package as possible for the packets to work, as they are no good in a large room, as there is probably more moisture than they could. They basically can absorb so much moisture before being useless. There is information online about recharging them though.
What about bugs/vermin? Bugs may decide to take up residence in your machine. At least, that happened when I stored my computer in a shed for a winter (in northern WI, where it is significantly colder than TX). But it should be okay.
Maybe make sure your data is secure? Backup all your critical data in the event that the computer is stolen/destroyed/compromised?
Otherwise, I think your'e fine. I'd use some compressed air post-storage to clean up the case, make sure all PC cards are seated, and make sure it's good to go.