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.

December: Early Summer Slump

December rounds out the year with conditions similar to January. Average swell height 2.3m, period 11.3s. Swell direction is heavily skewed to the south: SW 27.0%, SSW 15.6%, S 9.9% – a combined 52.5% from non-optimal directions. The preferred WSW sector delivers only 7.4%. Ideal wind sits at a paltry 9%. SSE wind again dominates at 32.2%, often strong. December surf is largely mediocre, with small, wind-affected waves. The occasional longer-period SW groundswell can produce fun sessions, but they are rare. It’s a month best suited for the dedicated local with a log or a groveler.