I went out cruising in Dayville (Northeast of NYC) about two days ago...
The bank sign termometer sais it was 103.
(it lies. It couldn't have been over eighty)
With that said, I was perfectly comfortable in jeans and a tank top, with a Propel in the bottle cage. I kicked around for a couple of hours until I started getting a mild sunburn. I think I'll be just fine in the summer heat up here.
But yes, humidity makes all the difference...
I've hiked the Grand Canyon in 120, felt chipper as a whistle, and barely dragged myself down the driveway in TN at 95 and high humidity.