**Forecast consensus for Wellington on September 18 points to a minimum temperature clustered in the 7–9°C range, aligning closely with the market’s tightest odds around 8°C (28.5%), 9°C (26.5%), and 7°C (23%).** Official guidance from MetService and multiple global models (including GFS and ECMWF runs) shows overnight lows near 7°C under partly cloudy skies, light northerly winds shifting southerly, and minimal cloud cover that permits moderate radiational cooling. This follows a period of slightly above-average September temperatures in Wellington, with recent days featuring highs in the mid-teens Celsius and lows rarely dipping below 8–10°C. Historical climatology places the typical September minimum near 9–10°C, so the current setup reflects a modest cool anomaly driven by clearer conditions rather than a strong cold outbreak. Model spread remains modest, with some guidance allowing for 6°C or 10°C depending on exact wind timing and cloud evolution overnight, which explains the dispersed but still concentrated probabilities. Resolution will hinge on the official overnight minimum recorded at the Wellington airport or Kelburn station, with final confirmation expected shortly after midnight local time.