Hanalei Bay seasonal overview
Best Surf Season (October - March)
The North Pacific roars to life during these months, as the Aleutian Low strengthens and sends a relentless barrage of long-period NW and NNW swells toward the Hawaiian Islands. Hanalei Bay, with its exposed northern orientation, captures the full force of these powerful winter storm trains. Average swell heights hover between 2.4m and 2.7m and periods consistently climb into the 11-13-second range, delivering powerful, grinding lines that peel perfectly across the reef. The main challenge is the persistent trade winds that blow from the east and northeast, which are onshore and can chop up the surface. However, when a cold front pushes through or a low pressure stalls to the north, southerly and southwesterly breezes set up offshore conditions, glassing off the bay for epic sessions. This is Hanalei at its finest.
Fair Surf Season (April - May & September)
As the North Pacific storm track begins to weaken in April, the average swell size drops off to around 2.1m and periods shorten to about 10.5 seconds. The window for quality waves narrows, but there are still plenty of fun, rippable days, especially when the swell direction shifts more northerly. May sees a further decline in size and period, but the wind ideal percentage climbs to 40% as lighter easterly trades and occasional southerly flows create more clean windows. September marks the return of the North Pacific, with a noticeable uptick in NNW swell (7.7% of the total) and longer periods around 9.3 seconds. The wind ideal percentage jumps to 54%, the highest of any month, making September a hidden gem for groomed, medium-sized surf.
Low Surf Season (June - August)
Summer in Hanalei is defined by the strong, persistent ENE trade winds that blow directly onshore, creating messy, choppy conditions. The swell is dominated by short-period (7-9 seconds), small (1.6m) ENE windswell that barely wraps into the bay. The wind blows from onshore quadrants over 90% of the time, with ideal offshore winds from the south occurring rarely (less than 1% combined). While the ocean may look inviting, the surf quality is generally poor, with weak, sectiony waves and bumpy surfaces. Only the occasional south swell or a rare north pulse can salvage a session, but these are few and far between. This is the time to travel or explore the south shore of Kauai.
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Conditions at Hanalei Bay in December
December: Winter Peak in Full Swing
December delivers winter at its finest. The average swell height is 2.6m and period 12.5 seconds, with a very high percentage of swell coming from the prime northwest and north-northwest directions – NNW (16.0%), N (4.9%), NNE (8.2%), NW (5.1%). These long-period groundswells pack tremendous energy and produce some of the largest, most powerful waves of the year. The wind ideal percentage is 36%, similar to November, as the trade winds are strong (E at 27.7%, ENE at 18.6%) but are periodically interrupted by cold fronts that usher in southerly winds (S 1.9%, SSW 1.7%). The best days come when a high-pressure system slides east and allows light variable or south winds to accompany the swell. This is the time for charging the outer reef and scoring the wave of your life at Hanalei.
Average Spot conditions at Hanalei Bay in December
Swell history for December
Wind history for December
Swell quality
Analyze the groundswell consistency at Hanalei Bay during December. Based on historical data, there is a % probability of groundswell occurring this month. The chart below provides a detailed breakdown of the average wave height distribution, offering deep insights into the swell quality and surf potential you can expect at Hanalei Bay for your next trip in December.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Hanalei Bay for December. Our analysis shows that favorable offshore or side-shore winds coincide with surfable swell approximately % of the time. The accompanying graph illustrates the average size distribution of waves during these optimal wind windows at Hanalei Bay.
