Hello Isaiah! Our thickest gloves, which are the 5mm ones, could only keep your hands warm when the temperature is over -5℃ (23℉). Since you need gloves that could work at -20 degrees, we think these gloves aren't suitable for your work. Apologies for that and we hope you understand. But please know that we're just an email away for any other questions or concerns you may have. Thanks and keep safe!