Above freezing. In Minnesota’s colder climate, Great Grandpa Donnelly said, “No stucco between Thanksgiving and Easter!” After browning and finishing coats set, stucco must not be exposed to freezing temperatures for 24 hours. Crumbling stucco indicates it likely froze during the setting period. On this, we always err on the side of caution. My kids often ask if I’m a weatherman or a stucco contractor because I'm always analyzing the weather.