Trader consensus on Polymarket has locked in a 100% implied probability for Seoul's highest temperature reaching exactly 18°C on May 2, backed by official observations from the Korea Meteorological Administration (KMA) at stations like Jongno, where daytime readings peaked at 18°C amid persistent cloud cover that capped solar heating. This follows May 1's clearer skies yielding near 24°C highs, with forecast models from KMA and global ensembles like ECMWF initially projecting 20–22°C before revising downward on intraday satellite imagery showing thick overcast suppressing convective warming. Early May climatology typically sees highs around 20–22°C, but such cloud-induced variability is common; a realistic challenge would require rare post hoc data revisions from KMA audits, though official tallies from 9 a.m. to 5 p.m. local time confirm resolution.