score:7
So I'm afraid all the best dive spots in Malaysia are out in Jan-Feb. As you've discovered, it's monsoon season on the east coast of the Peninsula, as well as at the famed dive spot of Sipadan in Sabah, Borneo. The weather is better on the west coast and in some bits of Sarawak, like Miri, but the diving is not that great any time of year.
The good news is that if you're got 150 euros for flight tickets and are already in Kuala Lumpur, the whole of Asia is your oyster thanks to Air Asia!
The obvious nearby option is the Andaman Sea coast of southern Thailand around Phi Phi, easily reached with flights to Phuket and Krabi, where it will be dry season, and you'll be just past the mad Xmas/NY rush so prices will have settled down as well.
Most of the Philippines and some off-the-beaten-track bits of Indonesia like Pulau Weh in Aceh are also dry as well. Bali and nearby will be wet though, as is the diving mecca of Bunaken up in Sulawesi.
Upvote:0
I did my open water certification & advanced open water certification at the beginning of January 2015 in Mabul island. Yes, one straight after another.
The weather was incredible, 30 degrees Celsius every day, not a drop of rain. Note that at the exact same time it was raining a LOT on the north west side of the island (Kota Kinabalu area) every day from 14:00 until late in the evening.
The diving instructors (nor anyone else) did not mention having some mandatory break at the end of January (c.f. Jpatokal's answer).
I also dived in Sipadan around the 7th of January 2015. It was incredible, a must do, but you must have an advanced open water certification.
Just call one of the diving schools in Mabul island to have further details. I highly recommend Scuba Junky, very nice people, very professional, provides good accommodation (& different ranges), and they help the local community.