Weather is probably a major factor when you plan your trip to Sumbawa Barat, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually October and November with an average temp of 80°F, while the coldest months are August and July with an average of 79°F. The rainiest months in Sumbawa Barat are January, February, December, and March, with each month seeing an average of 10 inches of rainfall.