We discuss microclimate biases («poor station exposures») in our «Has poor station quality biased U.S. temperature trend estimates?» (globalwarmingsolved.com)
Did such poor station quality exaggerate the estimates of global warming? (scientificamerican.com)
Thus, although poor station quality might affect absolute temperature, it does not appear to affect trends, and for global warming estimates, the trend is what is important (scientificamerican.com)