Sumner Avenue • Statistics for January

January: Deep Winter, Offshore Grooming

January at Sumner Avenue is the heart of the winter surf season. The average swell height is 1.4m (4.6ft) with a period of 7.0s, which means short-period but punchy, rideable waves. The swell rose is broad, but the S and SSW sectors lead the way (9.7% and 8.7% respectively), and the favorable ESE-S window totals about 27% of all swells. The real story is the wind: WNW and NW directions account for a combined 30% of observations, and with N/NNW flow added, offshore winds appear 44% of the time. That translates to the 28% 'ideal wind' days where cold, clean northwesterlies groom the south swell into lined-up peaks. Air temperatures average just 1.8°C (35°F) and water temps are a bone-chilling 5.2°C (41.4°F), so thick rubber is essential. Average precipitation runs 2.86 mm/day, often as snow or rain with passing fronts. Expect glassy but cold sessions whenever low pressures track offshore and the wind clocks northwest.