The title asks for the temperature in Seoul, but the resolution rules explicitly use data from the Incheon International Airport Station (RKSI). Being coastal, Incheon Airport's temperature can differ significantly from downtown Seoul, creating a trap for users who only read the title. Additionally, the requirement for whole degree Celsius precision could introduce rounding disputes.

Predicting the exact highest temperature of a specific location on a given day is a niche weather prediction market. While such markets exist, they are not mainstream topics compared to politics, economics, or sports.

May 4, 2026 - May 5, 2026, the price of the 18°C option surged from around 32c to 92.5c, while the 19°C option plummeted from a peak of 50.5c to 8.5c. This occurred because, as the May 5 resolution day arrived, real-time temperature recordings at Incheon Airport confirmed a daily high of approximately 18°C (64°F). The removal of forecast uncertainty prompted traders to heavily buy into the 18°C bracket. Between May 3 and May 4, 2026, the prices of the 16°C and 17°C options plummeted from around 27c to under 3c, and from 28c to 6c (before slightly rebounding to 14c), respectively. Concurrently, the 19°C option surged from 18c to roughly 40c, and the 18°C option spiked from 17c to a peak of 42c. This shift occurred because updated short-term forecasts indicated warmer clear-sky conditions, pushing the expected high for Incheon Airport to the 18°C-19°C range and causing the market to aggressively price out lower temperature estimates.

May 1, 2026 - May 4, 2026: The price of claude-opus-4-6-thinking surged from 73c to 96c, while options like Other, claude-opus-4-7-thinking, and gemini-3.1-pro-preview plummeted from 25c-29c to below 3c. This was caused by the approaching deadline confirming claude-opus-4-6-thinking's sustained #1 rank, virtually eliminating the chances for an upset. May 1, 2026 - May 2, 2026: The price of claude-opus-4-6-thinking surged from 73c to 94c, driven by its sustained dominance on the LMSYS Chatbot Arena leaderboard and increasing market confidence as the resolution date approaches. Concurrently, other competing models (e.g., claude-opus-4-7-thinking, gemini-3.1-pro-preview) saw their prices plummet by more than 10c down to near 1c, reflecting their fading chances of taking the top spot.

May 4, 2026 19:38 - May 4, 2026 23:58, the price of the 80-81°F option surged from 26c to 45.5c, while the 78-79°F option plummeted from 38c to 19.5c. This was due to evening updates in weather forecasting models, which revised the expected high temperature for the following day upward by approximately 2 degrees.

Between May 4, 2026, 23:58 and May 5, 2026, 02:08, the price of the '66-67°F' option plummeted from 43.5c to 19.0c, driven by some morning weather updates marginally adjusting the expected high downwards (towards 64-65°F). Between May 4, 2026, 15:18 and May 4, 2026, 19:38, the price of the '68-69°F' option surged from 5.5c to 13.5c, due to temporary midday warming forecasts that prompted bets on slightly higher temperatures.

Significant divergence exists. Wunderground explicitly forecasts a high of 67°F for KLAX on May 5, yet the implied probability for the '66-67°F' range is only priced at 19% in the market. Conversely, the '64-65°F' option is heavily favored at 44.5%. This indicates that the market is undervaluing the likelihood of reaching the 67°F peak forecasted by the primary resolution source.

Mainstream weather forecasts indicate the low temperature should confidently land in the 74-77°F range, yet the market assigns significant probabilities (prices around 13-15c) to options above 80°F. This divergence is likely due to illiquidity or traders mispricing the market based on an overestimated intuition of Miami's early summer heat.