September is a transition month between monsoon systems. On the West Coast of Peninsula Malaysia, the Southwest monsoon begins to lose its grip, although September still sees high rainfall levels.

On the East Coast likewise, September usually sees the onset of the Northeast monsoon.

In Borneo, September is also a perfect time to visit much of the island for long sunny days and clear skies. Rainfall is usually low in much of Sabah, making this a good time for a tour of Borneo or for visiting offshore islands such as Lankayan or the dive islands further south.

Areas such as the Danum Valley and the Kinabatangan River are usually ideal at this time of year.

On the North Coast of Sabah around Kota Kinabalu some afternoon showers can usually be expected every other day or two.

In Sarawak, drier weather continues, making this an optimum month for a tour of Borneo or visit to the wildlife lodges in Sabah or Sarawak.