I spent a lot of years working in aircraft corrosion control. In many (most) locations, the paints and chemicals were stored in outside metal sheds or cabinets without climate control, and were subjected to freezing as well as +100 degree temps. We also had to keep check on shelf life. As with any government operation, there were set procedures for evaluating paints/chemicals that were either past shelf-life or subjected to temp extremes.
For paints, the procedure was:
1. Open container and thoroughly stir the contents. If it blended well (in the case of pigmented paints that would normally separate in storage) and was free of lumps, it passed test one. If not it was disposed of.
2. Apply the coating to a clean dry surface. If it separated, or would not go evenly, it failed.
3. Let cure. If it dried within the normal drying time, and had the gloss/flatness and hiding characteristic is was supposed to, it passed, and we could use it. If it didn't cure, or was sticky or soft, it was disposed of.
For shelf life purposes, we were allowed to extend the shelf life 50% of the original for two times maximum.
We used this method on lacquers, enamels, polyurethanes and epoxy coatings. I have subsequently used it also for varnishes and enamels that have skinned over, being careful not to get the skin pieces in the paint, or straining it afterwards, all with good results. (This includes Behlens Rock Hard Table Top finish, which is notorious for skinning over within hours of opening the can).
We didn't use latex paint in my work there, but I have used a lot of it since. With latex, if it mixes up well, I use it, and have used some up to ten years old. I have touched up repairs on both the interior and exterior of my house over five years after the original painting, using paint out of the original containers, with excellent color and gloss match.
The one coating that in my experience does survive extended storage much past the shelf life is shellac in solution.
Key is to try some on a test piece. If it covers well, flows out, and dries like it's supposed to, it will be fine.
jmtcw
Go
PS. As previously stated, an old refrigerator or freezer makes an excellent storage container for coatings in this climate, to help mitigate the temperature swings.