I lived in DC for 4.5 years and the peak summer weather there was as bad as MS. Difference was the peak summer weather was a shorter window. I remember going to phish shows in Wisconsin back in summer 03-04 and people up there talking about the heat and humidity. We all thought it was perfect, ha.
I will say for the handful of days in Portland that the temps are in the mid 90s or higher and the temps don't drop to around 60 or lower like normal, it can get rough without A/C, but that's only a couple days per summer. Most days that the temps hit 95+, it still gets down to 60 at night to give some relief.

