Sines seasonal overview
Best Surf Season (October - March)
Winter brings the Atlantic to life, with average swell heights consistently over 2m and periods averaging 12-13 seconds, delivering powerful, long-period groundswell. Although the dominant swell direction is from the NW (which doesn't directly hit the south-facing beach), the frequent passage of strong extratropical cyclones dragging fronts across the Iberian Peninsula often produces pulses of S-SSW-SW swell that wrap perfectly into Sines. Combined with a higher incidence of offshore winds from the north quadrant (N, NNE, NE, NNW), the result is a 50-52% chance of ideal conditions. This is the prime window for pumping, firing waves in the 1.5-2.5m range, and occasionally XL days when the Atlantic aligns.
Fair Surf Season (April & September)
During the transition months of April and September, the storm track starts to shift, yet the ocean remains active. Average swell heights drop to 1.8m (April) and 1.4m (September), with periods around 11 seconds – still yielding solid, rippable waves. The Azores High begins to build or retreat, leading to a more mixed wind regime. Offshore winds from the north still dominate about half the time, but onshore southerlies become more frequent. These months are a classic gambler's window: you might score a clean, long-period SW swell with light N winds, or you might face smaller, choppier conditions. Best for the intermediate surfer looking for fun waves without the winter crowds.
Low Surf Season (May - August)
The summer months are defined by a strong Azores High, which suppresses the Atlantic storm machine. Average swell heights bottom out at 1.3m and periods slip to 8-9 seconds – small, fun-sized waves that require a grovel board. The upside is wind quality: with the thermal low over the Iberian Peninsula, north winds blow consistently, making offshore conditions (N, NNE, NW, NNW) the norm. In fact, ideal wind percentages peak at 55-61% in this period, meaning many days deliver clean, micro-to-small surf. While you won't chase XXL swells, this is the season for quiet morning sessions with smooth, rippable lines, especially on a longboard or fish.
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Conditions at Sines in April
April: Transitional Groveling
April sees a clear drop in size: average height 1.8m, period 11.2s – fun, rippable waves. The wind ideal percentage remains at 50%, but the wind directions are more varied: NW (15.9%) and NNW (15.5%) dominate the offshore component, while SW and WSW winds become more notable (5.2% and 6.0%). Swell from the crucial southern sector (S to SW) increases to about 1.7% – still small but a positive trend. The dominant swell is still NW (34.7% pure NW), meaning most days offer average, punchy waves best on a shortboard. This is a transition month where you can get a few bigger, long-period pulses if a late-winter storm tracks south, but overall, expect smaller, less consistent conditions.
Average Spot conditions at Sines in April
Swell history for April
Wind history for April
Swell quality
Analyze the groundswell consistency at Sines during April. Based on historical data, there is a % probability of groundswell occurring this month. The chart below provides a detailed breakdown of the average wave height distribution, offering deep insights into the swell quality and surf potential you can expect at Sines for your next trip in April.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Sines for April. Our analysis shows that favorable offshore or side-shore winds coincide with surfable swell approximately % of the time. The accompanying graph illustrates the average size distribution of waves during these optimal wind windows at Sines.
