The Dunes - surf spot statistics

Best Surf Season (May - August)

The Southern Hemisphere winter ignites the South Atlantic, with powerful extratropical cyclones firing long-period swell trains toward the Cape. During these months, the average wave period climbs to a peak of 12.6s in July, while average swell heights hover around a solid 2.8–2.9m. Critically, a higher proportion of swell arrives from the optimal WSW to NW window, with combined frequencies exceeding 14% in May and June – nearly double summer figures. Simultaneously, the frequency of ideal offshore winds from ONO to SO reaches its annual maximum, with ‘Wind is ideal’ readings hitting 24–25% in May and June. This is when The Dunes truly fires: long-period groundswells wrap in, groomed by clean SE breezes, producing pumping, firing waves in the 1.5–2.5m range.

Fair Surf Season (April & September)

These transitional months see a gradual shift in atmospheric patterns. April still enjoys a decent push of westerly swell (WSW + W ~9.3%) and a relatively high 20% ideal wind frequency, while September retains a solid 2.7m average swell height from the lingering winter swell machine. However, wind consistency drops (16% ideal), and the swell direction begins to swing back toward the SSW–SW quadrant. Conditions can be fun, rippable when the alignment is right, but expect more variability and occasional onshore slop.

Low Surf Season (October - March)

Summer dominates this extended period, with the South Atlantic storm track retreating southward. Swell direction remains stubbornly anchored in the SSW–SW quadrant (60–70% of all swell), which only indirectly wraps into the WNW-facing Dunes. The average wave period drops to 11.1–11.6s – still rideable but lacking the punch of winter. Worse, the wind regime is dominated by strong SE to SSE winds (often 20–40+ kph), which, while technically offshore, are frequently too beefy for clean conditions, leaving only 9–14% of the time truly ideal. The result is frequently choppy, messy waves with occasional small, fun-sized windows for the dedicated.

April: The Window Widens

April marks a meaningful shift. The average wave period jumps to 12.2s, indicating more long-period groundswell. Swell from the optimal WSW–NW sector now accounts for 9.9% (WSW 7.6%, W 1.7%, WNW 0.5%, NW 0.1%) – nearly double March’s share. Ideal wind availability reaches 20%, the highest yet, with a healthier mix of SE and lighter NNW winds. Although SSE wind is still the most common (25.7%), its intensity often drops. The average 2.4m swell height means solid, rippable waves on the better days. April opens the door to quality surf at The Dunes, especially when early frontal systems align.