**Forecast models and official guidance point to a maximum of 13–14°C in Wellington on August 27, 2026, as a southerly airstream follows recent northerly flow.** Current observations show temperatures near or slightly above seasonal norms after several days with highs of 14–17°C under northwesterlies. A trough and associated front are introducing cooler southerly winds, increasing cloud cover and the chance of showers, which will suppress daytime warming. Multiple sources, including MetService-aligned outlooks and Met Office guidance, indicate a daytime high near 14°C, while some numerical guidance (e.g., WeatherBug) leans toward 12–13°C under the overcast, showery regime. August climatology features average highs around 13–14°C, so the expected conditions represent a modest cool-down from the recent warmer spell rather than an extreme deviation. With resolution tied to the official highest recorded temperature, trader positioning heavily favors the narrow 13–14°C band because forecast uncertainty centers on the exact timing and strength of the southerly change and any breaks in cloud cover. Updated model runs and MetService briefings in the final hours before the date will be the key near-term drivers of any probability shifts.