I stick with good ol' trusty "have a good morning/afternoon/evening/etc". The statement will change depending on circumstance. Sometimes, when I'm feeling daring, I try a "have a good weekend", but this is risky. Different religions believe that the week ends on different days. I could very well offend someone if I wish them a good weekend several days before their week actually ends, or, god forbid, right after it ends. That would be a catastrophe.
And, under no circumstance do I say the names of the days of the week. Have you ever looked those up? They're all named after Gods. That's a trap waiting to spring if I've ever seen one.
Hmmm, If the j-man (you know who ... I'm not saying that name out loud) is the reason for the season (winter), then wouldn't that mean that it used to be significantly warmer before he came? If so, then couldn't he come back and cancel out this global warming trend? Just a thought.
ETA: Sorry about that tip. That really sucks.