I went to Indy for 12 straight years but got tired of it always raining..Have not been to the last 2 and don't miss the rain....I wish they would move it to a later time in the year........
Sept. when it is nice, dry and sticky would be great. About two weeks after the NHRA Nats. I agree wrong time of year for this nice of a show and racing.
i too have quit going to indy, spend a bunch of money and it always seems to rain one day or another,
In terms of watching out for rain? Not really, its pretty sporadic. I guess July is a little more dry, but it can rain at the drop of a hat in the midwest. FWIW, despite the rain, I always have a good time at GG indy, of course I'm a hop and a skip away.