I went for a 1000km (600 mile) ride this past weekend & in places it was 1.5C to 4C for over 200kms & my Gerbing T5 heated gloves kept my hands warm, not even a sign of cool air around my hands, they are on their 3rd winter with life time warranty on the heaters in the gloves they are worth the money.
https://www.youtube.com/watch?v=-0mCXiudCIE