Can urine or lure go bad if it’s left on a shelf in your garage, and you get some warm days (80-90 degrees) for a month?

Can they, yes. Should they, no. Keep out of direct light and know that everything evaporates, some things faster like skunk.

I’ve kept all my lures and urines and baits in an ungrateful, uncooled garage for years and they still produce just fine. Some of them even better with age.

I store all my lures In ammo can.

I use to believe it mattered till I lived in Arizona, the garage would get hot no matter what. if your lure could stand that heat over the summer months and still work in the fall/winter it was good. Then I started thinking about the lure dealers packing their products in trailers and u halls traveling the convention circuit, those lures are definetly cooked.

There was an old trapper in Arizona that kept his homemade lure in a container under the hood of his truck under lock and key, during season he would strip out glands and add to his brew, come summer the goop would cook in the Arizona heat along with the engine heat. His homemade goop caught a lot of fox and coyotes come fall.

I just keep mine in the garage and i have new bottles that are years old and never opened and i have some leftovers that i will grab and use the night before season opens with complete confidence

As Thorpe said put some on a stick and throw it on the shed roof and check it a month later, no smell no good.