Sumner Avenue - surf spot statistics

Best Surf Season (October - March)

The North Atlantic cranks up the energy in autumn, and by October, Sumner Avenue starts to feel the pulse of consistent groundswell. With average swell heights hovering around 1.3-1.4m and periods pushing into the 7-8s range, the combo of S/SSW/SSE swell and frequent offshore winds from the NW/WNW/N quadrants creates clean, punchy waves. This is prime time – the combination of solid swell and offshore flow peaks in December and January, delivering fun, rippable conditions on the best days. The statistical sweet spot runs from October through March, when the wind is ideal a solid 24-28% of the time and the swell window stays open. Expect average wave heights in the 1-1.5m range, often with enough power to hold a line, especially when period climbs above 10s.

Fair Surf Season (April & September)

April and September represent transitional windows at Sumner Avenue. In April, average swell height drops slightly to 1.2m with periods still solid around 7.3s, but the wind becomes more fickle – offshore flow drops to just 22% of the time. However, the S/SSE swell continues to deliver, and when a late winter low or early spring cold front aligns, you can score clean, fun waves. September signals the return of life after the summer doldrums, with average swell height climbing back to 1.2m and the longest periods of the year (8.4s). Offshore wind picks up to 28%, and the swell direction shifts to include more E/ESE contributions that can wrap in nicely. These months are hit-or-miss but offer quality windows for the patient surfer.

Low Surf Season (May - August)

Summer at Sumner Avenue is a mellow affair. From May through August, average swell heights bottom out at 0.9m, and periods stagnate in the 7.0-7.5s range. The dominant swell direction shifts to S/SSE, which is on the favorable side of the exposure, but the wind becomes the enemy. Onshore flow from the SSW/SW quadrants dominates, and the percentage of ideal offshore wind plummets to as low as 12-16% in June and July. Most days are plagued by weak, messy, short-period swell and onshore breezes that chop up the surface. While the occasional tropical storm or passing front can inject a pulse of energy, consistent quality is rare. This is the season for a longboard and a sunrise session on a rare clean morning.

September: Awakening of the Swell Season

September is the turning point. Average swell height jumps back to 1.2m, and the period reaches its annual peak at 8.4s, meaning more powerful, longer-period groundswell. Swell from the E/ESE dominates (17.7% and 18.0%), with significant contributions from SE (17.0%) and S (8.7%). Offshore wind frequency improves to 20.2% from the north quadrants, while onshore flow drops slightly. The combination of solid south swell and occasional offshore winds creates increasingly good conditions. Wave heights often fall in the 0.5-1.5m range, with long-period sets pushing into the 1.5-2m range on the best days. September marks the start of the quality season and should not be overlooked.