Ducklings are highly susceptible to cold temps. When starting, you will want your heat lamp set to 90 degrees. From there, you can go on one degree per day. On the other hand, most mature ducks perform best with temperatures of at least 55 degrees Fahrenheit. However - it's also critical to note that some cold-weather ducks tolerate (seemingly) icy weather - even as low as twenty degrees Fahrenheit. However, we advise giving your ducks more warmth than that - even mature ducks! (Even cold weather ducks are susceptible to frostbite.)