I have never had the entire windshield entirely fog up, though my car stays in a garage most of the time.

Usually the fog is from difference in temp from the outside to the inside. Now being so hot on the outside, if you keep the ac kicking on the front defroster it may cause that issues.

Though, in your case something different may be happening.

p.s. i assume this is happening while you are driving, if not maybe let the windshield thaw out before driving!