San Juan seasonal overview
Best Surf Season (May - June & September - October)
San Juan is not a spot where you chase huge swell - you chase surface conditions. The dominant E/ESE trade-wind regime is poorly aligned with this NNE-facing beach, so the best surfing comes when the winds relax and the texture cleans up. May and October lead the way with 40% and 37% ideal/offshore conditions, while June and September add 35% and 32% as transition months. Surf heights sit mostly in the 2-3ft (0.7-0.9m) range with average 6s periods, so expect small, rippable, fun-shaped waves rather than power. A longboard or groveler will be your best friend.
Fair Surf Season (November - April)
The winter half of the year is a study in trade-offs. Average swell heights edge up to 3ft (0.9m) and periods stretch to 6.2s, with a slightly higher ENE/NE component in the swell rose. That means more north in the water and occasional 3-5ft (1-1.5m) pulses when cold fronts and negative NAO patterns push North Atlantic energy into the Caribbean. However, the trade winds are also more established, and ideal wind percentages slip to 19-30%. You have to pick your windows carefully: the S/SW offshore days during winter are often San Juan's cleanest combination of size and shape.
Low Surf Season (July - August)
Midsummer is the slowest and sloppiest stretch of the year. The Bermuda High pumps the trades hardest from the E/ESE/ENE, ideal wind drops to 18-22%, and wave quality suffers despite water temps peaking at 28.4-28.8°C. Swell heights still average 2-3ft (0.8-0.9m), but periods hover around 6.0s and the constantly side-shore wind keeps the surface lumpy. Unless a hurricane or tropical wave aligns perfectly, low expectations are the right expectations.