Vietnam to Singapore in January

[Lagoon hound]

Appreciate any advise on sailing conditions in the South China Sea during the New Year / January Monsoon period (Vietnam to Singapore).

We are delivering a sailing catamaran early next year back to Singapore so keen to hear from those that have experience sailing these waters that time of year.

Have already lots of info re May to Oct ,but keen to hear the Monsoon period.

cheers
Andrew