You might spend a lot of your vacation inside, but if you want to see more of the area, looking at local weather trends is a good idea. The hottest months are usually September and October with an average temp of 83°F, while the coldest months are January and February with an average of 82°F. The rainiest months in Arno are July, November, October, and June, with each month seeing an average of 16 inches of rainfall.