Temps can get down to -20F in Madison at the extreme, with frequent mornings of -10F. And my fingers tend to get cold in gloves, so I wear thick ski mittens. My bike is set up so I can work the gears and brakes in mittens, with a big globby Shimano thumb shifter.

When it's warmer, I switch to something else, and I keep a pair of brown cotton work gloves in my sag bag for repairs, and in case it turns cold or windy during the spring and fall.

In my view, it's important to keep the insides of mittens dry, so I turn them inside out when I get to work, and back at home. In that sense, fabric gloves inside some sort of waterproof mitt might be preferable.