Boulder and Fort Collins, Colorado are very similar cities. They are college towns close to each other, at the same elevation, about the same size, and both situated up against the foothills of the Front Range.
But there are a couple of big differences. Fort Collins is growing rapidly, and its temperature station is poorly sited in a parking lot in the center of the city. As a result, Fort Collins has a serious UHI problem, and Boulder doesn’t.
Fort Collins has warmed four degrees since 1950, while Boulder has cooled. None of the standard techniques for UHI estimation would have detected this huge discrepancy, and if data from one station was filled in to replace missing data from the other one, the result would be grossly incorrect.