Conditions at Mejillones in September
September: First Signs of Autumn Fire
September is the month when the big ocean starts to wake up. The average period jumps from 8.1s in August to 10.0s, and average height remains a modest but rideable 1.4m (4-5ft). The directional picture is excellent: NNW accounts for 57.4 percent of all swell, NW 9.8 percent and N 21.0 percent, so Mejillones is already seeing the first long-period pulses from the North Atlantic. Wind is still predominantly NNE (49.0 percent), but the intensity is lower than mid-summer, and ideal wind improves to 5 percent. Water temperature is at its warmest of the year at 23.0°C, air temps average 22.9°C, and rainfall is still low. This is an underrated surf window: the tropics haven't fully left, the swell is rebuilding, and the odd S/SSW wind day can deliver surprisingly clean, warm-water surf.
Average Spot conditions at Mejillones in September
Swell history for September
Wind history for September
Swell quality
Analyze the groundswell consistency at Mejillones 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 Mejillones for your next trip in September.
Ground swell
Ground swell by size
Wind conditions
Evaluate the wind and swell alignment at Mejillones 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 Mejillones.