Compared to October, November will be slightly drier and lesser chances of typhoons blowing through. Monsoon season starts from June all the way to October. After October, things start to dry up. Most typhoons that occur in the Philippines takes a diagonal path from the Pacific on the eastern side of Leyte or Northern Mindanao, hugging or slicing through the Bicol province and continuing through the island of Luzon at the middle or on the northern tip before proceeding to Taiwan. Sometimes typhoons directly hit Manila or Southern Luzon (directly affecting Puerto Galera) but not most of the time. Typhoons can occur any time during the monsoon season. You can dive during the monsoon season as long as it is not windy and the waters are not choppy. If you plan to do land treks while on your dive trip, I would say November would be a safer bet than October for good dry and cool weather. But, the weather can be unpredicatable so there could be wet days during November and even a typhoon during December.
I usually visit the Philippines after the New Year festivities on January. Water temps are still warm (for me, locals find it a bit cool). According to my log book bottom temps were 26-deg.C during January/Feb (the coolest months). So, I would say water temps during October or November will be slightly warmer if not the same.
