Things are starting to dry out across the island during April, May and June with resplendent flowers and jungle foliage providing a totally tropical backdrop to any hiking or wildlife watching trip.
July is Borneo's festival month with loads of local vacations across the island meaning shops and banks maybe closed so bear this in mind if hoping to secure accommodation on the hoof.
August and September are still relatively dry, especially in the south of the island, but being prepared for a shower or two is definitely the best way forward. Forest fires will also become more prevalent during the dry summer season so please take all due precautions if you suffer from respiratory problems or want to avoid the, often stifling, smog.
October, November and December will see rainfall charts start to creep up again the further north you are but don't let this put you off as there are plenty of rooms available for what is generally considered to be Borneo's low season.
Mount Kinabalu's summit can be off limits at any time of the year due to poor weather conditions so keep your eye on relevant reports or opt for alternatives, such as Laban Rata, where climbing may still be permitted.