Consider declaring a 1D histogram like
TH1D* hist = new TH1D("Stats", "Temp. per day at 12 in 1988; Day; Temperature [#circC]", 366, 0, 366);
Is it possible to include parameters in the title setting part? This is part of a function that takes an hour (12 in this case) and a year (1988) and draws a histogram.