Last year I posted “San Juan Puerto Rico, EXACTLY how UHI warming can get into global gridded T trends” . I should have added this Fig 4 from Duchon’s 86 paper that I refer to.
There is IPCC AGW shouting out from the UHI affected San Juan trend, incorporated by Jones et al and the IPCC of course.
The trends below in Fig 4, from smaller places show little warming. Data are of poorer quality in a technical sense, but that is where the truth is.