**Trader sentiment for the lowest temperature in Wellington on August 31 reflects tight clustering around 5–8 °C, driven by an incoming southerly change that will replace mild northwesterlies with cooler air from higher latitudes.** Official guidance and ensemble forecasts indicate a daytime maximum near 14–16 °C followed by a rapid evening drop as winds turn southwest, with overnight lows most likely between 4 °C and 7 °C depending on the precise timing of the front and cloud cover. Clear or partly cloudy skies after the change would enhance radiational cooling and favor the lower end of the range, while scattered showers or lingering cloud would limit the drop and support readings closer to 7–8 °C. Model spread arises mainly from differences in the speed of the cold-air advection and boundary-layer mixing, producing the observed market balance (5 °C or below at 39.5 %, 7 °C at 34 %, 8 °C at 27 %). Historical climatology for late August shows typical minima near 9 °C, so the current setup represents a notably cooler-than-average night whose exact value hinges on short-term forecast adjustments expected in the next model runs.