2016 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 3 12 3 4 6 10 11 3 11 9 7 3 82 Monthly Average: 6.8 Partial 4 4 8 5 10 4 3 7 8 9 5 4 71 Monthly Average: 5.9 Spectroscopic 2 5 4 2 4 6 2 0 0 5 1 2 33 Monthly Average: 2.8 Cloudy 22 8 16 19 11 10 15 21 11 9 17 22 181 Monthly Average: 15.1 ------------------------------------------------------------------------------- Clear Hours 63 153 65 62 88 91 90 69 146 152 120 64 1163 Monthly Average: 96.9 Clear+Dark Hours 47 107 9 31 25 38 62 51 63 81 47 46 607 Monthly Average: 50.6 Mean Consec 1.5 2.4 1.5 2.0 1.5 2.0 5.5 1.5 2.8 1.5 1.8 1.5 Monthly Average: 2.1 Max Consec 2 5 2 3 3 5 6 2 5 3 2 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.