The warmest winter gloves are often the ones with nice insulation, that are water resistant or waterproof, are breathable, and cover at least your wrist. Here are attributes for the warmest winter gloves to keep your hands protected during the blistering cold.
The warmest winter gloves should have some sort of wool or fleece lining since wool and fleece are warmer materials, and are soft on the skin. Insulation is important otherwise you just have an outer shell for your gloves which wouldn't be very warm at all.
Water resistant or waterproof material is important to keep moisture out, especially if you're out in rain or snow during the winter, which can be brutal. Your fingers are most likely to freeze in this type of weather if you don't have gloves that can resist or prevent water from getting in. If your fingers get wet, the cold will get to them quicker, causing you a lot of discomfort.
The warmest winter gloves are also breathable but wind resistant because you don't want heat and moisture to get trapped, which can cause a lot of discomfort, but at the same time, you don't want to let cold air in. The warmest winter gloves let your hands breathe so you don't have to take your hands out of your gloves to get some fresh air, and since you can keep your hands in your gloves at all times, you'll keep them warm.
The best winter gloves cover at least your wrist for extra protection since gloves that don't cover your wrists allow some cold air to flow in through the gloves' opening. Good gloves are also built that they are fitted around your wrist and aren't loose so cold air is less likely to get in. Your gloves should also be long enough that they meet with or slip under your jacket sleeves for more protection from the cold.