Weather is probably a major factor when you plan your trip to Jombang, but bear 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 temperature of 25°C, while the coldest months are August and July, with an average of 24°C. The rainiest months in Jombang are January, February, December and March, with each month seeing an average of 580 mm of rainfall.