Weather will likely play an important role when you plan your trip to Santiago de Vigo, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July with an average temp of 65°F, while the coldest months are February and January with an average of 50°F. The rainiest months in Santiago de Vigo are December, October, November, and January, with each month seeing an average of 10 inches of rainfall.