Capital Weather Gang's NatCast has 'Gotta wonder if attendance will take a hit on a day like this. At least you're not playing? Seek shade, cold drinks and A/C when possible!' - 102-105 at first pitch, 97-100 by ninth inning, 10% chance of rain.
weather.com is showing heat index of 104-106 over those periods.
Thankfully TBSITH is under shade from 14.30 onward.
(And of course after this series is up the highs get down to the 80's - but that's the All-Star break and then a Nats away trip at Miami...we just can't catch a break from the weatherman!)