The question of the effects of la Nina on the NE Pacific came up last year - probably every year - and the word from NOAA was that it didn't really affect the NE Pacific.
I have had the good fortune to sail in and out of Hawaii a couple of times, but in the summer. Some good friends sailed from San Carlos
, Sonora, Mexico
(essentially Cabo San Lucas by the time you get around the Baja
peninsula) to the Marshall Islands
in February, and essentially got the stuffing pulled out of them. They tried to go it all in one shot but had to stop at Johnston Island for repairs
. Their crossing was at a latitude of about 16 degrees.
What you have to deal with is climate, which favors storms at that time of year; you may have been lucky with the weather
before, you may be lucky again, but you should plan on some heavy weather
once and a while on that trip.