PairedHistogram[WeatherData["Chicago", "MeanTemperature", {{2011, 1, 1}, {2012, 7, 31}, "Day"}, "Value"], WeatherData["NewYork", "MeanTemperature",{{2011, 1, 1}, {2012, 7, 31}, "Day"}, "Value"],{1},ChartLabels->{Placed[{"Chicago", "New York"},Above],None,None},ChartStyle->{54, None, None},ImageSize->550,BaseStyle->{FontFamily->"Helvetica",FontSize->16},PlotLabel->"Mean Temperature in Celsius from 2011 to August 2012",PlotRangePadding->{{0,0},{5,7}}]