Knees and Climate

In my village, we judge the seasons by an examination of the postman's knees.
As soon as the temperature rises a few degrees Celsius (or whatever system you use) above freezing, he takes off his trousers and dons his shorts.
Those knobbly knees tell you that winter is over and that spring, if not summer, is on the way.
Mind you, there's a vicious north-easter blowing this morning. At this rate, his knees are not going to last long.
PS Mrs Duck is back, but with only eleven fluffies this time. At the moment they are all tucked warmly underneath her. THEY aren't fooled by the postman's knees.