my own preference would be:
E420 (they already took care of one of the main bugaboos!)
E500 (this would be first if i could afford it.)
I'd say that's normal. In hot weather that temperature will go over 100, specially when you've been cruising then hit stop and go traffic as will a bunch of other common heat generating activities...
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"