Mundaka is a world-class left-hand river mouth wave that thrives on powerful, well-organized ground swell and favorable wind conditions. The data shows that the best months for surfing here are from October through March, when ground swell dominates (65-85% occurrence), mean swell heights range from 1.3m to 1.8m, and the likelihood of good wind conditions peaks at 30-31% (compared to the summer lows of 19-23%). Winter months, particularly December to February, offer the most consistent and powerful swells, though wind conditions remain challenging (69-72% bad winds). Spring and summer see a sharp decline in quality, with increasing wind swell dominance, smaller waves (0.8-1.2m), and worse wind odds (74-81% unfavorable). September marks the transition back to better conditions, while April through August are generally inconsistent due to higher wind swell influence and onshore winds. For experienced surfers targeting Mundaka's legendary barrels, the prime window is autumn through early winter when the Atlantic swell engine is most active and wind chances slightly improve, despite still being predominantly marginal. The spot's reliance on precise sandbar formation means these stats only tell part of the story, but the trend clearly favors late fall and winter for the biggest, cleanest sessions.