2023 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 9 3 1 5 9 17 11 4 11 16 7 2 95 Monthly Average: 7.9 Partial 1 5 5 12 6 2 2 4 7 8 8 12 72 Monthly Average: 6.0 Spectroscopic 2 2 0 4 2 3 2 1 0 3 2 2 23 Monthly Average: 1.9 Cloudy 19 18 25 9 14 8 16 22 12 4 13 15 175 Monthly Average: 14.6 ------------------------------------------------------------------------------- Clear Hours 106 71 31 129 95 128 89 48 134 221 107 98 1257 Monthly Average:104.8 Clear+Dark Hours 57 27 26 57 30 80 49 13 61 136 51 49 636 Monthly Average: 53.0 Mean Consec 1.8 1.0 1.0 1.3 3.0 3.4 3.7 2.0 2.2 2.7 1.4 1.0 Monthly Average: 2.0 Max Consec 4 1 1 2 9 11 7 3 4 5 2 1 Monthly Average: 4.2 ------------------------------------------------------------------------------- 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.