My follow up: Rode on Sunday 55 miles to camp at a state forest and then back yesterday. It was the hottest riding day of the year for me here in the Boston area on Sunday, and I was pretty cooked by the end. Yesterday was cooler and overcast, and it started raining a few minutes after I got home.
I was on my Waltly Ti bike with 700 x 38mm wheels and good carrying capacity:
This morning I did a brief ride with a friend to enjoy some really nice weather. I was on my Milwaukee single speed: