January to September is the dry season. A year brings 1,800 to 2,200 mm of rain on average, and the mountains get more rain than the flat land.
Floods usually happen from September to November. The air is most humid in October and November and least humid in June and July.
On the bad days, leave the bike at home and take a taxi or a Grab car. Keep some cash at home too, because card machines may stop working when the power goes.