Crab Island seasonal overview
Best Surf Season (October - March)
The North Atlantic delivers its full fury during these months, with average swell heights pushing 2.0m to 2.5m and periods exceeding 11 seconds. Powerful low-pressure systems track across the Atlantic, generating consistent groundswell from the west and northwest that pounds Crab Island's west-facing beach. The dominant wind flow is from the south to west, which unfortunately is onshore for this spot. However, when a high-pressure ridge builds over the British Isles and the Azores High extends north, we see clean offshore winds from the east and southeast, especially during cold snaps. These windows, though rare (14-17% ideal wind), produce epic conditions with long-period, organized swell. The best bet is to watch for a negative NAO pattern that brings easterly winds.
Fair Surf Season (April - May & September)
Spring and early autumn offer a trade-off: the swell drops off to fun-sized 1.2-1.5m with periods around 10 seconds, but the frequency of favorable offshore winds increases. April sees the highest percentage of ideal wind at 21%, often from the east-northeast as pressure gradients relax. The waves become more manageable, making this a great time for longboarding or groveling on small days. September marks the transition back to bigger swell, but the wind patterns are still mixed, yielding a higher chance of clean conditions than mid-winter.
Low Surf Season (June - August)
Summer brings the smallest swell of the year, averaging around 1.1-1.2m with short periods (8.7-9.1s). The North Atlantic storm track shifts north, and the prevailing westerlies weaken. What swell does arrive is typically weak windswell from the west, quickly chopped up by onshore sea breezes. Ideal wind percentages drop to 13-16%, and even when the wind comes from the east, the waves lack power. Expect micro to small, grovelly conditions. Occasionally a distant hurricane or tropical storm can send a pulse of longer-period swell, but those events are rare. This is the season to explore other spots or take a break from surfing.
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Conditions at Crab Island in December
December: Winter Peak
Average swell 2.3m, period 12.2s. Swell direction: W 24.2%, WSW 15.4%, WNW 11.7%. Wave heights are big: over 1.5m for a large portion. Ideal wind remains at 14%. Wind pattern similar to November, with strong onshore flow. However, the frequency of easterly winds is slightly higher (E 5.4%, ESE 5.5%). Christmas swells are a real possibility if you can time the weather windows. This is the peak month for power and size.
Average Spot conditions at Crab Island in December
Swell history for December
Wind history for December
Swell quality
Analyze the groundswell consistency at Crab Island 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 Crab Island for your next trip in December.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Crab Island 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 Crab Island.
