2006 Toyota Corolla Serpentine Belt Squeal

My serpentine belt squeals on some days, but not all. It seems to be related to the weather. There is much more frequent and loud squealing on cool, wet days. Sometimes it goes away as the car warms up, but not usually. I had the belt changed less than 2 years ago, and it started squealling again within the first year of the replacement. I generally don't expose it to stop-and-go traffic or harsh driving conditions. I just had an oil change a few days ago, and they said all the belts look to be in good condition. Could this be a problem with the tensioner? Any help would be greatly appreciated. The car seems too new and to have too few miles to be going on to a 3rd serpentine belt.
Thank you for your time.