2024 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 2 0 1 13 15 12 7 5 12 7 5 5 85 Monthly Average: 7.1 Partial 9 8 6 9 8 3 0 1 10 9 9 9 81 Monthly Average: 6.8 Spectroscopic 1 2 2 0 2 3 6 0 5 3 3 5 32 Monthly Average: 2.7 Cloudy 19 19 22 8 6 12 18 25 3 12 13 12 169 Monthly Average: 14.1 ------------------------------------------------------------------------------- Clear Hours 74 46 43 164 153 97 50 46 172 133 122 119 1219 Monthly Average:101.6 Clear+Dark Hours 34 25 18 71 61 44 46 16 86 95 53 77 626 Monthly Average: 52.2 Mean Consec 1.0 0 1.0 1.9 3.0 2.4 3.5 1.7 1.7 2.3 1.0 1.7 Monthly Average: 1.8 Max Consec 1 0 1 3 7 5 6 2 3 3 1 3 Monthly Average: 2.9 ------------------------------------------------------------------------------- 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.