Didn't Sept 2017 put up like a 7 day stretch of 90+? It was also late Sept too I believe, which makes it one of the most impressive heat events in Chicago's history imo. Also the same year we had the incredible February warm spell too.

it'll end up being a Rockies ridge more than likely. We just can't seem to get these huge ridges to form in the Midwest anymore for some reason, yet the east and west both roast. I do agree with you on the implications of poor farming practices back in the 30s, but @Grizzcoat is also likely correct in the increased water vapor making it exceedingly difficult to attain these super high max temps. Maybe a severe drought could come close to producing those temps nowadays, but we're not headed for a drought anytime soon.

Same logic for PDX. Average July max 11˚F cooler, yet has reached 116˚F in June. So somewhere in the 125–135˚F range is probably doable at Pasco given the correct set-up.

Given that the average July max temperature at Pasco is 8˚F warmer than at Lytton, and Lytton has reached the 120˚F mark in June, 125˚F in July seems completely doable for Pasco.