Having a lot of expereince in colder climates, feel like I can offer:

Between 25 and 45 I use a light full finger pair of REI gloves really just a wind cover, hands stay toasty warm

Colder than that full finger REI cycling gloves with some insulation.

With both, its important that you move your hand around more than normal, because you fingers get shoved all the way into the gloves causing a lack of circulation. I even occasionally stop and slightly pull my hands out of the glove ever so slightly so the fingers are not pressing against the ends of the glove. Also, gloves should fit somewhat loosely so that there is an airspace for insulation