bees get cold they cannot produce enough energy in their wing muscles to fly. They will fall to the ground, or land on something and wait for it to get warmer so they can fly.
Air Temperature - If the air is very cold the bees will gradually become cooler as they fly.Light Intensity - This may vary a little from the race of bee to race of bee but it is a general rule.
Sugar Sources - would phone me every few months to have bees removed.Free Glucose - Stainless steel is a funny metal and develops metal fatigue easily.
Generally, bees are inactive outside the hive when it is cold or dark. Bees come out when it is warm and light enough for them to do their work. If it is cold, they pop out to go to the lot.