This is my second winter commuting so I decided to make a chart of what I wore that works at various temps. I used increments of 5 degrees Farahenheit. Now that spring is coming, I find the chart very useful in seeing what to wear when the temps dip low sometimes...I suspect the chart will be very useful for the next winter. I get a lot of anxiety fretting about what to wear sometimes... here's what I have, though it probably won't make much sense without seeing them. But you get the idea:

10F - Full mask, merino , cashmere, wool pants , double socks , double gloves, neck warmer
15F - Full mask, cashmere, wool pants , double socks , double gloves
20F - 3/4 mask, merino, wool pants , single socks , double gloves
25F - 1/2 mask, merino, wool pants , single socks , single gloves
30F - 1/2 mask, merino zipper half down, wool pants , single socks , single gloves
35F - 1/2 mask, merino zipper 3/4 down, , single socks , single gloves ( thin liner )
45F - 1/4 mask, merino zipper 3/4 down, , windbreaker pants no under thermals, single socks , liner gloves

to make it more complete, you'll need to factor in humidity and wind chill.

Any rules of thumb on humidity, I never thought about that one?

Humidity in Maine during the winter is either really dry or really wet. Until it gets above 45F, I don't really pay attention. I agree with wind chill. I very rarely wear any kind of face mask, and only a bacalava if the wind is howling or wind chill is below 0F.

My one big weakness is extremities: hands and feet, with my toes being the worst.

I do something similar. I keep a spreadsheet of my rides, noting information important to me. Part of that is a comment about the temperature, the clothes I wore and other things that I think might matter later. It's pretty simple, usually just copy, past and edit a couple things.

Cold air holds so little water vapor that humidity will not be much of a factor.

yeah, unless you live near a pond.

higher humidity will have the same effects of sweaty clothing during winter, only not as drastic.

Huh - I don't worry about windchill or humidity during the winter either, the humidity only gets noticeable when it's warmer, and when I'm already going 15mph on my bike it's only very rarely that the wind gets strong enough to even notice it. Plus I'm already wearing windproof-ish clothing...

Windchill is irrelevant on the bike imho. It's better to factor in wind speed and direction. If the wind is at your back it will actually negate the windchill you would've otherwise faced. Conversely if it's in your face you need to account for the 'extra' wind you generate when moving.

A clothing chart is a good idea. I find myself 're-learning' how to dress every year of course for me so much depends on perception/conditioning of cold. ie 10F in fall is freaking cold. In spring 10F is warm!

Is this just perception or reality? Does the human body slowly acclimate to cold temperatures as the winter progresses? Are there any specific physiological changes that occur? I hope I wont have to modify my chart for this Fall/Winter!

I'm no expert, but I'm pretty sure it's reality - In the fall I would wear a long sleeve shirt over a t-shirt when it was 45 degrees, and i was freezing for the first few minutes. Now, I wear a T-shirt and shorts and don't feel cold at all.

I do the same thing. I keep a clothing log of what I wear in different temps. Makes for a quick reference when the next winter season comes around. That way I know what works and what does'nt. Good idea. Pass it along.

Glove choice seems to need the most fine tuning. I have a couple pairs of winter gloves that seem to do alright in the 40's, but below that I put on a pair of shell over mitts (3 finger type). Sometimes I have to cram so handwarmers in there as well. I need to make a chart to show when I need what hand protection. And under 40, I always need booties and double socks.

I have made 1 degree (Celsius) chart.
Temperature Clothing Chart - notebook

This simple chart has worked well for me.