It's raining more now as Indonesia entered the rainy season so expect the following:
Riders will stop under bridges, underpasses, trees to shelter from the rain as they don't have rain coats or the intelligence to carry rain coats so traffic becomes congested
Riders tend to ride even more erratically due to being in a hurry not to get wet
Those with ponchos will not realise that their bikes indicators can no longer be seen so be careful going round them
Riders will make more sudden moves as they deserve lot the way of puddles which could put holes
However, there are lots bike riders in the rain so the roads are slightly less full.
Cars will go slower for those brave enough to let their cars get wet in the rain but have a tendency to drive more in the middle of the road.
Personally if I can I will ride in the rain as there is less traffic and seek out the bus lanes as they are still empty and the police won't be ticketing anything when there is a storm.
But remember as soon as the rain stops then everything starts up again and the traffic gets worse as noone likes to get splashed or ride in the wetter parts of the road.