If you really want to get serious about late season hunting, nothing compares to fur. I made some fur mittens and have yet to have my hands get cold while wearing them, but like someone else mentioned above, a light glove under the mitten is needed so your warm clammy hands don't freeze to your bow when really cold.

Also another thing that allows me to stay out longer is what i call a my "hobo" heater, a circular tin can of some kin, take a roll of cheap toilet paper, remove the center carbord thingy, shove tp in the tin can ( perferrable a tight fit so it fills up the center hole), take a bottle or two of rubing alchol and completely saturate the tp, put lid on tin can, when your colder than balls out hunting, get it out of your pack and light it up to thaw yourself out a tad. it's a smokeless, odorless, and for the most part soundless heat source.... and when all else fails, try real hard to shoot a deer in september so your done by now..lol