The absolute best months to visit the Cliffs of Moher are May, June, and September. During these "shoulder" months, you have the highest probability of clear skies and manageable winds, which are essential for actually seeing the cliffs, as they are often shrouded in thick Atlantic fog. May is particularly beautiful because the wildflowers are in bloom and the days are getting longer, but the peak summer tourist crowds haven't yet arrived. September offers a similar balance of decent weather and slightly thinned-out crowds. While July and August are the warmest, they are also incredibly crowded, often leading to a "one-in-one-out" policy for the parking lot and packed viewing platforms. If you must visit in winter, be prepared for extreme gusts that can lead to temporary closures for safety. Regardless of the month, the best time of day to visit is either before 10:00 AM or after 4:00 PM to avoid the large tour buses from Dublin.