[DeepThought]

If it's just the initial hit then maybe you can wash your face a few times with cold water before getting in, exposing them gradualy.
If it comes from a prolonged exposure, maybe try getting one of those ice caps (do a search and look for a picture of a gimp diving).
Maybe with time the sensation will start apearing later and later till it won't come back...

I have 0 expirience with cold water, so just speculating outloud.