Depending on the weather, they could be trying to keep the hive cool. It is typical to see bearding and/or bees trying to keep the hive cool this time of year in Georgia as the night time (and day time) temps get warmer.
What is their ventilation like? (screened bottom board, etc.) Also, where are you? Please alter your profile to list your location, right now you are in "no man's land" :).
Best,
Derrick