Notes
70* and 90% humidity to start (although the streets were wet and water was steadily streaming off my roof so think the humidity was closer to 100%) and 72* and 78% humidity to finish. I could tell when the humidity started dropping because it felt like a 20 pound backpack had been lifted off me!
This was scheduled to be an 18 miler but I felt so good up in my hill neighborhood that I tacked on another loop to make 19 miles. Then when I got home I still felt good so tacked on some more to get over 21 miles and could have kept going. Awesome! If the race is 72* and 78% humidity with 100% cloud cover 9mpm would probably be my marathon pace.