**Trader consensus on the Cape Town highest-temperature market heavily favors 17°C or below because real-time observations and official forecasts show the day’s maximum remaining at or below that threshold.** On September 9, 2026, Cape Town International Airport and other stations recorded afternoon temperatures around 15–17°C under overcast skies and persistent southerly winds of 15–25 km/h, consistent with a cool maritime air mass typical of early spring. Multiple forecast models (including those from the South African Weather Service and international guidance) projected daytime highs of 16–19°C but with limited insolation due to cloud cover and strong onshore flow, keeping actual peaks at the lower end of that range. This aligns with the broader September climatology of average highs near 18°C, though recent days had been warmer before the current regime shift. The near-certain market-implied probability reflects the strength of the observational data and model agreement at this late stage of the day. A realistic scenario that could still alter the outcome would require rapid clearing and reduced wind speeds allowing additional solar heating in the final hours, though current conditions make that improbable.