Foz do Arelho is a consistent surf spot with reliable ground swells throughout the year, though conditions vary significantly by season. The best months for surfers are typically from October through March, when ground swell dominates (75-91%), swell size averages 2.0-2.6m, and wind conditions, while still often unfavorable, offer slightly higher chances of clean surf (24-28% good winds). Winter months like January and December stand out with the largest swells (2.5-2.6m) and the highest ground swell consistency (85-91%), though strong onshore winds remain a challenge (72-75% bad winds). Spring and summer (April-September) see a steep decline in quality, with wind swells taking over (60-84%), smaller waves (1.4-1.7m), and fewer clean wind days (12-18%). September and October mark the transition back to better conditions, offering a balance of decent swell size (1.6-2.0m) and ground swell influence (46-66%). For advanced surfers, the winter season provides the most powerful and consistent waves, but patience with wind conditions is key. Late autumn (November) and early winter (December) may offer the best compromise between swell size, ground swell purity, and slightly less harsh winds.