Are the horns under the headlight assembly like the earlier models or are they behind the front bumper cover? One of them blew and I got this high pitched nearly inaudible sound coming from my horn.

 

Check behind the front bumper area.What happens is, moisture gets blown into the horn and it gets harder and harder to vibrate and "work'.
Sometimes you can get it to work better again if you tap it a few times to free up the vibrating pieces. If that fails replacement may be the only alternative.
Covering the horn with a towel or rag will help protect your sanity if it decides to work while you are still under the front of the vehicle.

 

thanks I'll check it out. What do you think about using compressed air to clear it out?