At Adak, overcast conditions average nearly 75 percent of the time during June and July, dropping back to approximately 50 percent of the time from October through February. Adak averages 173 days per year with fog. The foggiest months are July and August when an average of 26 of the 31 days have fog. This number drops dramatically toward the winter season where the months of December through March have, on average, fewer than ten days with fog during any one month.