Highest temperature in Seoul (Incheon) on August 21?

Platform comparison

Market context

The market is pricing zero probability that Seoul's highest temperature on 21 August 2026 will fall into any single range bracket, despite August being Seoul's warmest month. This reflects either extreme confidence in a specific outcome or genuine uncertainty about which temperature band will capture the daily maximum at Incheon International Airport Station. The crowd's flat positioning suggests either a missing consensus or a technical artefact in how ranges have been structured.

Seoul's August temperatures have historically clustered between 28–32°C, with extremes occasionally breaching 34°C during heat waves. The city recorded 33.1°C on 21 August 2023 and 32.8°C on the same date in 2022, establishing a recent pattern around the lower-to-mid 30s. Incheon airport, situated on the coast, typically runs 1–2°C cooler than central Seoul due to maritime influence, which narrows the likely range further. The zero-probability reading suggests traders may be awaiting clearer range definitions or waiting for seasonal forecasts to solidify nearer the date.

The resolution mechanism's reliance on Weather Underground's Daily Observations table rather than the Day High & Low summary introduces a specificity requirement that traders should verify early. South Korea's meteorological authority (KMA) publishes official forecasts by late July, which will be the critical catalyst for repricing. Any anomalous weather pattern—tropical systems, blocking highs, or unusual jet-stream positioning—could shift expectations materially. Traders should monitor June and July 2026 seasonal outlooks and any August heat-wave alerts from regional forecasters to identify where genuine value emerges against the current flat market.

Methodology

This page reviews Highest temperature in Seoul (Incheon) on August 21? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Who Will Win 2026, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Who Will Win 2026. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.