Nahoon Reef • Statistics for January

January: Summer Swells and Sticky Onshores

January brings the heart of the South African summer to Nahoon Reef, and while the ocean isn't short on energy, the quality control is mostly handled by the wind. Average swell height sits at 6ft (1.8m) with a 10.2s period, putting most surf in the punchy-to-powerful groundswell range. The E/ESE/SE/SSE window - the direction that really lights up this SE-facing reef - supplies just over half of the total swell energy, led by SSE at 14.7 per cent, E at 13.5 per cent, SE at 12.3 per cent and ESE at 11.6 per cent. There is also a strong S and SSW component, making up around 40 per cent of the mix and adding size and power, though at a more oblique angle. The catch is the wind: ENE at 21.0 per cent and NE at 16.7 per cent dominate, with those persistent summery trades and afternoon sea-breezes putting a crumble on the face. Offshore W/NW flow is a rare commodity, reflected in the 14 per cent favourable-wind figure. When a pre-frontal north-westerly does align with an E/ESE swell, expect clean, hollow reef waves, but they remain the exception rather than the rule.

Air temperature averages 22.9°C, water temperature is a warm 21.9°C, and precipitation at 4.33mm/day reflects the humid, showery summer regime. The combination of warm ocean and unstable air can trigger local thunderstorms that briefly flatten the wind and create surprise glassy windows.