Weather will likely play an important role when you plan your trip to Bac Son, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually June and July, with an average temperature of 28°C, while the coldest months are January and December, with an average of 18°C. The rainiest months in Bac Son are August, June, July and May, with each month seeing an average of 378 mm of rainfall.