I watched Dean Snell's YouTube video on this topic the other day (I've been ordering Snell balls for awhile, so I get the emails). Anyway, he stressed not leaving them in your bag, or in your garage, but rather store the balls indoors, because the optimum ball temp is 70-90 F. If you do that, it takes a long time for them to get cold. To the contrary, if you keep them in a 40 degree trunk or a cold garage, they will never warm up enough during the round. I'm gonna do both, keep inside then store in a large 'Yeti' (Wal-Mart knockoff) water bottle that has also been inside. Not to 'warm' them, but to slow down the rate at which they get cold.