Per Cindy Hamilton:
I live in Michigan.

I didn't go through the drudgery of listing my opinion
of still colder temperatures. Without bothering with
the conversion to Celsius:

50 need to wear a flannel shirt when working outdoors
40 need to wear a jacket when working outdoors
30 need to wear gloves when working outdoors
20 minimum grilling temperature, provided the grill is in the lee of the house
10 need to wear a hat
0 time to get out the Carhartt
-10 snot freezes right in the nose. Stay indoors if possible.

A bit like Canada?
http://tinyurl.com/y8qv9dn9
--
Pete Cresswell