Weather will likely play an important role when you plan your trip to Banjarmasin, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually October and September, with an average temperature of 27°C, while the coldest months are July and August, with an average of 27°C. The rainiest months in Banjarmasin are December, March, January and November, with each month seeing an average of 338 mm of rainfall.