Holy cow, 88F at 9:30 am. Nice... The morning commute wasn't that bad though. But I expect the afternoon to be a scorcher.

Last summer I had to ride without a helmet on the way home several times when it was over 95F. Although the helmet was ventilated and light silver color it was unbearably hot. In particular in Manhattan where it's often up to 10F hotter than the outer boroughs. Bandana under a helmet helps a bit keeping the sweat off your eyes but not so much for the heat. But if you don't wear a helmet then definitely wear a bandana or a cap.

And yeah, there is nothing wrong with taking mass transit or even staying home. Heat stroke is a real danger, in particular if you're not used to heat. Although, honestly, I'd rather be on a bike than on a NYC subway. I've been stuck on crowded subways in the Summer, often without power, the heat was unbearable, I saw people faint and myself felt like I was about to vomit, no water, no place to seat, no way to get out, freaking horrible. At least once I got home so sick I had to stay home the next day.

At least on a bike I can stop in a shade, walk into air conditioned store, get water, get ice, etc.