Surf forecastStatisticsHistorical report

Sao Juliao seasonal overview

Best Surf Season (October - March)

The North Atlantic roars to life during this six-month window, delivering the most consistent and powerful surf of the year at Sao Juliao. Average swell heights range from 2.0m to 2.6m, with periods frequently in the 12-13 second range – a recipe for long-period groundswells that wrap into the WNW-facing beach with authority. The dominant swell directions are NW, WNW, and NNW, which together account for over 50% of the total swell energy in most months. This is when the jet stream is most active, spawning deep extratropical lows that send clean, lined-up waves to the Portuguese coast. Offshore wind conditions (from the E to SE quadrants) occur roughly 20-25% of the time, often during post-cold-frontal setups with light easterlies. When these align, expect pumping, heavy surf in the 1.5-2.5m range with epic, long-period waves that make the beach a world-class destination. The best windows are often in November, December, and January, when the NAO index can be negative, steering storms toward the Iberian Peninsula.

Fair Surf Season (April - May)

As spring arrives, the frequency of powerful low-pressure systems begins to wane, but the Atlantic still provides a steady supply of moderate-groundswell energy. Average swell heights drop to 1.7-2.0m, while periods shorten to 10-11 seconds, producing average, punchy waves that remain fun and rippable. NW and WNW swells still dominate, but the wind patterns become less reliable for perfect conditions. Ideal offshore easterlies occur only 9-12% of the time, as the dominant wind starts to shift from northerly (cross-shore) to more frequent sea breezes. Early-morning sessions often offer the best chance for clean faces before onshore winds pick up. This is a transition season – you’ll need to work for the good days, but when a strong spring storm aligns with a high-pressure ridge, you can enjoy solid surf with far less crowds than winter.

Low Surf Season (June - September)

The summer months bring a dramatic reduction in both swell size and quality. Average heights slide to a paltry 1.4-1.6m, and periods drop to 8-10 seconds – often producing choppy, weak, and messy waves. The swell direction remains locked in from the NW and NNW, but these are generally windswell or shorter-period pulses with minimal power. The real killer is the wind regime. A dominant northerly flow (N and NNW) sets in, blowing along the coast at 20-40 kph for the majority of days. This creates strong cross-shore to side-onshore conditions that spoil the wave shape. Ideal offshore easterly winds are a rarity, occurring only 2-5% of the time in July and August. The surf is generally limited to small, fun-sized groveling waves for the shortboard, or longboard glide on the rare, cleaner days. Dawn patrol is your only hope, as thermal-driven onshore winds develop quickly. With high pressure locked over the Azores, the summer pattern is reliable – but not for good surf. Plan your trip elsewhere or bring a log and low expectations.

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Conditions at Sao Juliao in September

September: First Hints of Autumn

September marks the beginning of the transition back to productive surf. Average swell height edges up to 1.6m and period increases to 10.5 seconds – now pushing into the average, punchy category. The swell direction still favors NNW (34.4%) and NW (36.0%), but there is a slight increase in WNW (15.4%) and W (4.4%) swell, indicating the first autumnal lows are becoming active. Wave heights are spread across the 0.5-2m range, with about 40% in the 1-1.5m range and 25% in the 1.5-2m range. Ideal wind conditions improve to 12%, as the northerly winds moderate. N wind is still dominant at 34.3%, but speeds are lower (10-30 kph more common). Offshore easterlies remain scarce (around 12% combined), but when they align with a building NW swell, you can get fun, clean waves for the first time in months. The key is to watch for tropical activity in the Atlantic that can send longer-period pulses, or early-season cold fronts that bring a shift to offshore winds. Late summer guests can still score light crowds and decent conditions if they pick the right day.

Average Spot conditions at Sao Juliao in September

Swell history for September

0 - 0.5
0.5 - 1
1 - 1.5
1.5 - 2.0
2.0 - 2.5
> 2.5 m

Wind history for September

0 - 10
10 - 20
20 - 30
30 - 40
40 - 50
> 50 km/h

Swell quality

Analyze the groundswell consistency at Sao Juliao during September. 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 Sao Juliao for your next trip in September.

Ground swell

Ground swell by size

Wind conditions

Evaluate the wind and swell alignment at Sao Juliao for September. 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 Sao Juliao.

Swell with good wind

Swell with good wind by size