Green, no matter how long...

[Yooper]

One thing that will help is to put the carboy in a tub of water. The water will help dampen the temperature swings. You can also drape wet towels over the carboy. The evaporation will help cool it. If you need a lot of cooling, put a cheap box fan on the carboy draped in the towels sitting in a tub of water. That'll cool it several degrees. Bonus: The water will carry the heat the yeast produce away better than air.

Exactly- I don't have a problem keeping things cool usually, but a bin of water surrounding the carboy/bucket will keep fluctuations to a minimum. In the winter, I can add an aquarium thermometer to the water to keep the fermenter warmer, or to bring up the temperature as fermentation ends.

I live in a cold climate, so I have no problems keeping my fermentations cool, but if you do (or you have a higher heat setting on your furnace!), you could definitely try putting the fermenter in a water bath in a bin or cooler and that will help quite a bit.