My wife told me when she goes through a heavy rainstorm her '01 V70XC AWD screams or screeches. She said she would pull off the road and shut the car off and when she started it again it was gone. I told her it was the belt so she had our mechanic check and he said the belt was fine. Well last night, I was driving with her and we hit a real wild rain storm. All of a sudden I heard a loud siren and thought a cruiser or ambulance was coming behind us. IT WAS HER CAR!! I never heard a car make a siren noise. It kept up for about one minute or less and got quieter then stopped. I've never heard a belt make this noise and I couldn't even tell where it was coming from. It was like all over the car. I told her not to stop the car because I wanted to try to pin it down which I never did. It was almost like wind blowing through a small opening or something. Believe me IT WAS LOUD. Any of you guys got any thoughts on what this might be. It was wierd. I never heard a car make a noise like this in my life.

 

It's called rain squeal. The exhaust expands and hits the driveshaft
Takeit to a Volvo dealer for the fix or remove the middleresonator and add a straight pipe

 

JRL - Thanks for pinpointing this. I had just added to a similar thread, but this one would have been better.