<30     thick gloves, lots and lots of layers (and my large bag+paniers so that layers can be removed and added easily)
<40     wool socks, full balaclava
<50     silk balaclava, full-fingered gloves, full pants (preferably windbreaker)
<60     windbreaker (preferably with lots of vents to be able to manage sweat buildup, but anything will do)