Growing waves need pushing winds from a common direction over an area of open ocean, called a fetch, for a sufficient amount of time, or duration. To make extreme surf, the four most important criteria are wind speed, fetch size, duration, and proximity to the target, ie., Hawaii. 

For creation of giant surf, winds thrashing the ocean surface must be nearly hurricane force, or 50-70 knots, for several days over a long area the distance of California eastward to Colorado, or over 1000 nm. Winds spiral inward toward the center of a storm's low pressure center.  A given bird's eye (or satellite) snapshot of surface winds shows a circular nature of winds around the center of low pressure.  Only a portion of those winds are aimed at a forecast target, such as Hawaii.  At any given time, the fetch length aimed at Hawaii is typically too short to produce giant surf, even if the speeds are mega strong.  However, there is a special condition that makes giant surf possible.

The growing seas and swell under the storm moving toward Hawaii have a speed of about 20-25 knots.  If the storm tracks at similar speeds in a direction toward Hawaii, which is common as storms leave the active generation zone off Japan in winter and steer eastward, then the same growing, eastward moving swells continually receive wind energy.  This is called a "captured" or "trapped" fetch, and allows the extraordinary wave heights to develop.

As swells leave the storm, the wave heights rapidly decrease, resulting in a drop in half the size over the first 1000 nm of travel.  Thus for giant surf to arrive in Hawaii, the storm track needs to be close to the islands.  Ideally the storm's fetch reaches to within about 300 to 500 nm before veering away from the islands, bringing in the giant surf, but keeping the local weather fair, giving ideal surf conditions.

If the storms get too close, the surf becomes "victory at sea", with overlapping waves of differing wave direction and periods arriving simultaneously, making for unfavorable surf.  At peak winter in January into early February, about 75% of the episodes either have light winds, trades, or southerlies making for ideal surf, with the other 25% arriving with strong westerlies to northerlies, creating havoc.