squealing belt

Can also be from a cold morning or humidity. But if it lasts too long then the belt is basically getting old. There really isn't a good way to deglaze a belt (unlike the old V belts) When you replace the belt take a good look at every pully and idler to make sure there isn't any junk left behind.

Depending on your model it could just take a breaker bar to hold the tension roller off while you swap the belt.

Older vehicles are a bit more complicated to set belt tension.