As someone who lives in Oklahoma and spent his early childhood in snowy New England, I would add one other suggestion to this great list. Think about extreme summer as being similar to extreme winter. When it's brutally hot and humid sometimes the best answer is to cut that 100 mile ride down to 60 miles. We don't think twice about such a strategy in extreme winter, but in the peak of summer we want to believe we can just power through it. But we need to be aware that summer, like winter, can create conditions we sometimes should just avoid. That said, I do love long solitary summer afternoon rides.