I think it was in a children's book, one of the Henry and Mudge series by Cynthia Rylant maybe. There was a chapter about a day like this one that we're having right now, and it was called "Wet yuck."
A more optimistic description is the one that weather forecasters often use - "wintry mix."
A wintry mix sounds like a party in December, or maybe a lovely pine-scented potpourri, or perhaps some kind of hearty granola. Would you rather go for a walk in wet yuck, or pine-scented potpourri?
Given the choice, I guess I'll take the optimistic point of view (even though wet yuck says it pretty well).