Humid. I was on vacation last week, so this was unwelcome. Got to work rather damp and it took me about half an hour to feel like my core wasn't melting down.

I rode with a commuter on a road bike. He didn't know I was behind him until about 3 miles after I caught him. He turned his head and did a double take at me. Then he sped up from ~15 to ~20MPH but I stayed with him anyway. Not too close though. Eventually we split up, and then I saw him riding in to an office building behind my office building when I was already inside. I guess he wanted to take the more urban (and longer) route.