Sumatra Travel Tip No. 18 Sumatra’s wet and dry seasons aren’t strongly defined – there can be rain often in dry season, and a lot of hot, sunny days in wet season. That means, you never quite know what to expect! One essential item to always tuck into your backpack is a light rain jacket or poncho – especially if you’re heading out on a scooter adventure or a hike. You can buy wet weather pants and jackets at most Indomarets or convenience stores for just a few dollars. And don’t forget dry bag