Lately, I've been having trouble with freezing my hands when it wasn't that cold outside. Because of some unusual problems I was having that go beyond simple cold fingers, I saw a doc. She told me that I need cover my wrists and forearms better when riding because getting those too cold will cause me to freeze my fingers even if I'm wearing warm gloves.
Today, commuting conditions were nippy (24F and foggy accompanied by light headwinds) so I decided to see if the advice works. The difference was incredible. Rather than having the normal freezing finger problems, they were warm and even a bit sweaty. So, if you're having trouble freezing your fingers and your gloves should be heavy enough, you might try protecting your wrists and forearms better.