emm, I feel your pain! I don't have as severe as you, but looking at some hot spots on the deck. Is there any way you can have some sun shield? Watering is an immediate relief, but doesn't deal with the issue. A side note is the bigger the pots the better. I suggest 12" min, and about equally deep. Any less will cook. Can you hang a neat college theme/color sail? Breathable light cotton comes to mind. Or go retro tie dye, see that's back in fashion.
I'll think of more. As it happens, need to work my deck yesterday, perhaps starting this wkd, and as it is now warm can wear my tie-dye t-shirt. But I digress.
Think positive, and it will get just more hot. HaHa!!!!