The stations on the map are uniformely distributed, and the temperature trend is a clear representation of the climate status of the region.
Oklahoma has seen a clear cooling of 0.285º F (0,14º C). There was a couple of weather stations (Boise City and Kenton) that showed a warming of 1.7º F and 2.0º F. The "urban heat island" is not a matter of simply how big has the city grown, but how has the growth affected the location of the sensing thermometer in the station. If the station has been surrounded by an area of avenues and building that re-radiates the sun's energy (and lots of heat in summer when many air conditioners are working) this extra heat will influence the thermometer. That surely explains the observed warming in both cities - but how can we explain the strong cooling in many cities in Oklahoma? Any suggestion other than a natural overall cooling?
Global warming means there is an overall warming everywhere in the world, but there must be a reason for the cooling in some regions - reason that has not been explained by any climate model. As CO2 is blamed for the temperature increase and, as CO2 has increased steadily, there shouldn't be any cooling anywhere. As we see cooling in many places around the world, the relation between CO2 and temperature increase is a false one.
Furthermore, as the relation between CO2 and temperature is derived from computer models, these climatic models are not an accurate image of the climatic system, and they cannot give an accurate prediction of the future climate.