Forecast models from MetService and NIWA currently indicate a minimum temperature near 9–10°C in Wellington on August 23 under northwesterly flow, with showers clearing to fine conditions that limit nocturnal radiative cooling and keep winds elevated overnight. This setup explains the tight clustering of market-implied odds around 10°C, 8°C, and 15°C or higher, as small shifts in wind strength, cloud cover, or shower timing can alter the low by 2–3°C. August climatology shows average overnight lows near 8°C, but recent polar air outbreaks have given way to milder advection, increasing uncertainty in ensemble guidance and keeping probabilities for extremes like 5°C or below competitively priced despite lower baseline likelihood. Updated model runs and MetService briefings ahead of the overnight period represent the next key data points for traders.