What temperature do you switch from your normal warm weather gear to your cold weather gear?

My 'normal' gear is:
- fingerless gloves
- bike shorts
- bike shirt/compression shirt (short sleeve)

That is usually good down to about the upper 50s, maybe 55 or so. Once it drops below that, I put on the microfleece long sleeve and tights. I can usually keep the fingerless gloves down to about 50, but then I get out the full length gloves (Izumi Pearl is what I have now).

If it gets down to the mid 40s, or wet in the 50s, I have some heavier tights and wind/waterproof jacket that comes out, but they are noticeably bulkier.

Once it gets below 40, the wind/waterproof tights and jacket are on regardless of conditions (water doesn't make much of a difference at that point), and I add my leather, water resistant motorcycle gloves.

If it's cold enough for ice/snow, I'm driving my AWD 4-wheeled cage.