Mount Washington in December

June through October gives you the best shot at decent weather, but even summer can bring snow to the summit. July and August are warmest, with highs around 60°F at the top — but pack layers because temperatures drop 3-5 degrees for every 1,000 feet you climb. September and early October offer spectacular fall foliage, but book accommodations months ahead. The Auto Road typically closes November through April due to weather. Winter brings extreme conditions — the observatory recorded a temperature of -47°F with wind chills reaching -100°F. Spring is mud season, with trails often impassable until late May. Check the Mount Washington Observatory website for current conditions before you go. Seriously, the weather here kills people who come unprepared.