Big vs. small dogs in hot weather

There's a stupid argument raging on my dog park's FB page about whether big dogs can deal with heat better than small ones (our small-dog section has much less shade and someone posited that the big dogs should be down there instead).

Just curious if it's true. I think/know big dogs can better withstand cold, but wasn't sure if it was the same for heat.

(Note that both sides have water during the summer and usually half a dozen kiddie pools show up at some point.)