It’s very possible that there’s both a UHI and elevation component. Downtown is at about 800 feet, the airport is at about 1200 feet and 15+ miles west of downtown. That’s why I can’t just dismiss that old data entirely, which it’s my understanding was taken at “various locations in the city” (I should know where and when, but I’m afraid I don’t). And I guess that’s the rub here. It’s not necessarily that I think the data is invalid, but I don’t think it’s all that useful to compare the data for the reasons listed above.