What is implied is that “six more weeks of winter” means six more weeks of cold, winter weather, which includes snow and ice. It is not a calendar-based saying. If he doesn’t see his shadow, then spring will come early (snow/ice/extreme cold will end soon). I’m a meteorologist (since 1980). We were taught such things in college. ;-)
Note the change from “CN” to “GN” on the microphone. “Gato” = cat.