I have used Mod Podge here in Arizona during the summer in 110 degree weather and it doesn't seem to be affected by the heat. Although, I don't think I have actually taken any of my Mod Podged items outdoors in the heat for a long period of time to even know what would happen to it. We keep our indoor temp around 80 degrees during the summer and Mod Podge isn't affected indoors. That was kind of a scattered response and I don't know if it helped you any!