From April 28, 2026, 14:03 to 17:18, the price of the 13°C option surged from 47.5c to 57.0c, as the latest weather forecasts closer to the resolution date leaned towards a lower maximum temperature. From April 28, 2026, 07:33 to 17:18, the price of the 15°C option plummeted from 18.0c to 8.0c, due to downward revisions in forecasted temperatures, drastically reducing the likelihood of reaching 15°C. From April 27 to April 28, 2026, as weather data updated, the market gradually priced in the cooling expectation, leading to a continuous rise in the probability of 13°C and a compression of probabilities for options 15°C and above.

Weather prediction markets are a niche but established category on such platforms. While everyone checks weather forecasts, placing bets on the exact daily high at a specific airport is mainly attractive to hardcore prediction market users and weather enthusiasts.

The title asks for the highest temperature in Seoul, but the resolution rules explicitly specify using data from Incheon International Airport (RKSI). Temperatures between Seoul city and the coastal Incheon airport often differ, posing a significant trap for traders relying solely on Seoul forecasts. Additionally, the rule uses whole degrees Celsius, introducing rounding risks.

April 28, 2026 - April 28, 2026, the price of 16°C spiked from 5c to 26c before falling back to 10.5c, and 13°C abnormally surged from 0.65c to 20.7c before crashing to near zero. This was likely due to short-term weather model updates or large trades hitting thin market depth. April 27, 2026 - April 28, 2026, the price of '19°C or higher' dropped from a peak of 53c to 38.5c, while '18°C' and '17°C' rose from 18.5c and 16c to around 28.5c and 25c, respectively. This shift occurred as updated meteorological data slightly adjusted the expected high temperature center from above 19°C down to the 17°C-18.5°C range.