Well, really there is because once you get towards freezing the gun has lost 99% of it's effectiveness. I have seen 2 Tanaka's (AICS and Kar98) and 1 Co2 Sigma used in 25f temps (off propane and green) and that was pushing the limit. They had dropped from high 500fps mark down to low 300's. Plus consistency was long gone. Still technically functional, but no longer useful really.
I would say minimum effective temp would be roughly 40f.