Next year's NFL finale will take place at the Metlife Stadium, the home of the New York Giants and the New York Jets, where average temperatures are barely above freezing during February.
The Baltimore Ravens quarterback told reporters: "I think it's retarded. I probably shouldn't say that. I think it's stupid.
"If you want a Super Bowl, put a retractable dome on your stadium. Then you can get one. Other than that I don't really like the idea.
"I don't think people would react very well to it, or be glad to play anybody in that kind of weather."
Flacco will play in his first Super Bowl this weekend in New Orleans under the roof of the Superdome.