I have in mind to ride from Ottawa to Seattle this season. Here's my planned route - I'm excited!

Doing it in August would fit with some family schedule things but I'm worried about the heat. I wasn't too worried about Northern US until I looked at historical temps for Rapid City SD. Last year Aug 10 was 103 degrees and the year before was high 90's. I don't mind the heat but that sounds like a bit much. Has anybody else made this run in high summer?