Haleiwa, located on Oahu’s North Shore, is a world-class surf spot known for its powerful, consistent waves, particularly during the winter months. The best conditions for surfing at Haleiwa occur from November through March, when ground swells dominate (76–91% of the time) and swell size averages between 2.0–2.4 meters. These months offer the biggest and cleanest waves, though wind conditions are less favorable, with good winds only occurring 24–27% of the time. Winter swells are primarily ground swells, providing long-period, well-organized waves ideal for advanced surfers. The peak season in December and January sees the largest swells, but strong onshore winds can occasionally disrupt conditions. From April to October, Haleiwa transitions to smaller swells, with wind swells becoming more prevalent (59–83% of the time) and average wave heights dropping to 1.2–1.7 meters. While summer months like June and July have the smallest waves, they also experience the worst wind conditions, with good winds occurring only 18–20% of the time. However, late summer and early fall (September–October) see a slight rebound in ground swell activity (41–64%) and more favorable wind conditions (29% good winds), making these months a secondary window for surfers looking for manageable waves with cleaner wind setups. Overall, the prime surfing season at Haleiwa is undeniably winter, when powerful ground swells deliver the best waves, despite less-than-ideal wind patterns. Summer offers smaller, less consistent conditions, though late summer and early fall can provide occasional surfable days with lighter winds. Advanced surfers will prioritize the winter months for high-performance surfing, while those seeking mellower waves might find September and October more suitable.