For years my 2001 drove me nuts when it rains the belts squeek. I changed the belts, made sure the tension was correct, and as soon as it rained and you went through a puddle, the belts started to slip and squeek. If you have this problem, check to see if the belt is the kind with notches on the inside.
Seems that type picks up grit and deposits it in the pulley, when it rains water gets in there and mixes with the grit and makes the noise. Change to a flat type, check the tension with a tension gauge per factory spec. and it goes away.