Weather will likely play an important role when you plan your trip to Arroyo Seco, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually July and August with an average temp of 63°F, while the coldest months are January and December with an average of 27°F. The snowiest months in Arroyo Seco are January, March, November, and December, with each month seeing an average of 10 inches of snowfall.