My son went to SERE in Maine the winter.  You have no reason to worry.  Your son will be fine.

My DS did SERE in the desert in the summer, so no, but the staff are watching them closely.  I won't say don't worry...hah...not possible.  But he will make it.  They won't let real harm happen.  But, I do remember that first phone call afterwards.  Major relief.  Prayer and distraction got me through.  Hang in there. 

Just  wanted to let you know that my son made it through SERE. But it was very cold, sub zero temperatures the whole time.