Porthleven • Statistics for January

January: Midwinter Atlantic Power

January is the midwinter peak of the North Atlantic storm track. The average swell height is around 8ft (2.5m) with a long-period average of 11.7s, so Porthleven is receiving powerful groundswell rather than local windswell. The wave rose is dominated by W (17.7%), WSW (12.8%), WNW (6.3%) and SW (6.1%). Much of this sits close to the optimal S-to-WSW window, though the W component can be slightly too west for the southwest-facing bay and often produces a more walled-up or cross-shore wave depending on tide.

The wind data reveal the classic winter struggle: SW (10.7%), WSW (10.8%), W (10.6%) and SSW (7.6%) dominate, which means onshore or cross-onshore conditions are frequent. Ideal offshore N/NNE/NE/ENE flow only scores 15% for the month. The clear sessions come when a transient ridge of high pressure builds between Atlantic lows, flipping winds into the N/NE and temporarily cleaning up the 6-8ft (1.8-2.4m) swell.

Water temperature settles at 10.0°C, air temperatures average 9.3°C, and precipitation runs at 3.45 mm/day. January is raw, cold and powerful; if you pick your windows, the reward is some of the heaviest surf Porthleven sees all year.