Plummet said..
January isn't the best time for waves. Usually they are smaller with less frontal driven swell.
That said. Prevailing wind is Westerly. Your best bet for the best waves will be the west coast. The best waves on the west coast is in Raglan and Taranaki. Taranaki works from ne to SE, but is best W, WSW and SE.
However some times in January there are easterly driven tropical systems. Then you will want yo look on the east coast!
Hopefully someone else will chime in on east coast spots.
Thanks Plummet. Any particular spots at Raglan and Taranaki you can share? Please PM me if you don't want to publicise any secret spots - I'll honour the privacy of local spots!
I've been searching for a decent website with historical wind data for New Zealand so that I plan to spend more time in those areas with higher wind stats. Any idea what website is best (so far it looks like windfinder is the only one with any info)?