Monsoons and Typhoons in Sundaland

When the winds shift and the rains start to fall the people of Sundaland celebrate the nourishment it brings to the land. They give thanks and offerings to their gods and enjoy festivities with their families. The weeks and months ahead will result in a bounty that is a reward for hard work and preparations made during the rest of the year.

- An Account of Sundaland by Alom Takal 

Monsoon Rains

Unlike Europe and North America the area of Sundaland does not experience four distinct seasons. Instead there are two Monsoon seasons, broadly speaking a warm and wet season and a cool and dry season, with some local variations in timing. The point is that the cycle of dry and wet seasons will be an important influence on the local culture as it is today where there are special festivities to celebrate the coming of the rains. These alternating seasons could be an influence on religion, festivities, ease of travel and war opportunities.

The monsoon rains are driven by prevailing winds which alternate in origin from the Southeast and Northwest directions with a curvature at the equator due to the coriolis force. As I mentioned there are local variations in terms of timing so I won't go into too much detail here. I've linked to climate pages for each of the countries in the region which will help you get an overall picture of the weather.  Remember that the average temperature of the planet was a couple of  degrees cooler during the last Ice Age and that it was dryer compared to now since more water was locked up in ice sheets. This means that rainy seasons are even more important than normal to the people of the central Sundaland plains.

I suggest you do a search for the area name plus 'climate' or 'monsoon' if you want more details. The climate of the central plain of Sundaland will fall somewhere in between the relevant landmasses.

North Australia
Papua New Guinea
Sulawesi
Java
Sumatra
Malaysia
Borneo
Philippines
Cambodia
Thailand
North Vietnam
South Vietnam
Myanmar
Southern China
Taiwan

Read more about the Malaysian-Australian Monsoon.

Typhoons

A typhoon is a tropical storm that develops in the Pacific Ocean and moves towards the west. The wind speed must be greater than 119 km ph / 74 mph for a tropical storm to be categorised as a typhoon. Peak months for typhoons are from May to October but they can occur throughout the year.

The areas most affected by typhoons are where the modern day countries of the Philippines, Vietnam, Cambodia, Laos, Hong Kong exist.

Besides the high winds other features of typhoons include tidal surges along the coasts and landslides in hill areas.