Most springs since I have lived in this area, there has been a day in early spring when I have gone running and found myself thinking, In July or August this will feel refreshing. The corollary of course is, But right now I'm uncomfortable. Last Saturday was one of those days.
The day's high temperature was about 80 F and the humidity was low. However, the trees looked to me to be maybe a quarter in leaf, so the shade was sparse, even where soon it will be dense. At Sheridan Circle I looked around to pick which side of Massachusetts Avenue to take up the hill, and conclude that it didn't matter. Nor did it seem to, for I saw no more shade on the side where I ddin't run than on the side where I did.
The humidity was low enough that I got home with a mostly dry shirt. Perhaps I gained a little in acclimation for the summer that is coming soon.