**Wellington, New Zealand—widely recognized as the world’s windiest city due to its exposure on the Cook Strait in the path of the Roaring Forties—experiences its windiest season during Southern Hemisphere spring (September–November).** A strengthening El Niño, with sea-surface temperature anomalies already exceeding +2°C and forecasts for a very strong or historic event through late 2026, is expected to enhance westerly flow and pressure gradients across the region, potentially increasing both mean winds and gust frequency compared with climatology. September typically sees average hourly winds rising from roughly 22 km/h early in the month to 24 km/h by the end, driven by the seasonal strengthening of the mid-latitude westerlies and more frequent frontal passages. Peak gusts, however, depend on the intensity of individual synoptic systems rather than averages; historical records at Wellington Aero show gusts exceeding 96 km/h on multiple days per year on average, with September contributing meaningfully to spring totals. The closely balanced market probabilities (near 50% across the three bins) reflect genuine uncertainty in the timing and strength of the strongest events this month. A relatively quiescent period with fewer intense lows could keep the seasonal maximum below 90 km/h, while one or two well-developed systems—favored by the El Niño background—could easily produce gusts in the 90–101 km/h range or push above 102 km/h. Early-September model guidance already indicates daily gusts in the 30–50 km/h range, consistent with the start of the seasonal ramp-up. Updated ensemble forecasts and any rapid intensification of the El Niño signal will be the key near-term drivers shifting sentiment among these thresholds.