Woolsey Hall, Yale University, which houses the Newberry Memorial Organ is not climate controlled and some listeners have the impression that the tone of the organ varies with the seasons. The present work measured the overall SPL, and the SPL’s of the harmonics of the C’s of a number of flue and reed stops of the organ in August and March, 1996 to determine possible seasonal differences. The C’s of flue and reed stops were recorded in the hall using a calibrated microphone and digital tape recorder system. The tapes were played into a computer, using Spectraplus 4 software, and the overall SPL levels of each C together with the SPL levels of the harmonics were extracted. The overall levels of 67 out of the 76 observations of the C’s were 0.5–14 dB higher in August than in March, confirming the impression that the organ sounds louder in the summer. In 55 observations higher numbered harmonics that were present in August were absent in March. These findings are compatible with the impression that the organ sounds brighter in summer.