2015 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 9 7 9 5 1 9 3 0 9 7 14 6 79 Monthly Average: 6.6 Partial 6 6 8 8 7 3 5 6 5 3 7 5 69 Monthly Average: 5.8 Spectroscopic 1 4 4 4 3 2 3 7 3 3 2 2 38 Monthly Average: 3.2 Cloudy 15 10 10 13 20 16 20 18 14 18 7 18 179 Monthly Average: 14.9 ------------------------------------------------------------------------------- Clear Hours 143 118 129 92 41 77 43 27 99 91 198 111 1169 Monthly Average: 97.4 Clear+Dark Hours 67 55 35 55 22 57 23 22 55 42 104 49 586 Monthly Average: 48.8 Mean Consec 1.5 1.8 3.0 2.5 1.0 3.0 1.5 0.0 2.7 1.2 1.8 1.2 Monthly Average: 1.8 Max Consec 3 4 6 4 1 6 2 0 4 2 5 2 Monthly Average: 3.3 ------------------------------------------------------------------------------- Definitions: Photometric - cloudfree dusk-to-dawn. Partial - at least 3 consecutive cloudfree hours during the night. Spectroscopic - less than about 1 mag. extinction throughout the night. Cloudy - cloudy. Clear+Dark Hours = photometric hours with moon absent. Mean Consec = mean number of consecutive photometric nights during the month. Max Consec = maximum number of consecutive photometric nights during the month.