Highest temperature in Seoul on July 21?

Platform comparison

Market context

The market tracks the peak Celsius temperature at Incheon International Airport on 21 July 2026, a specific metric sourced from Wunderground’s daily history for station RKSI. With the settlement window closing at 12:00 UTC on that date, the current 0% probability for any “YES” outcome reflects a binary misunderstanding of the market structure; this is a range-based resolution, not a simple yes/no event. Programmatic traders should parse the outcome space as discrete temperature bands rather than a single directional bet, automating queries against the Wunderground API to update position sizing as real-time data flows in.

Historical July data for Seoul shows average highs of 28°C, with a 43% chance of rain and 80% relative humidity creating a consistently warm, humid environment [2]. The Polymarket frontrunner currently sits at 27°C with 86% implied probability, while 28°C holds 10%, suggesting the crowd expects temperatures just below the long-term average [1]. A 0% crowd-implied probability for a generic “YES” likely indicates the user interface is misaligned with the actual resolution logic, where traders must select the specific range containing the peak temperature rather than betting on a binary outcome.

Key catalysts include the official daily temperature release from Wunderground at 12:00 UTC, which acts as the sole settlement trigger. Traders should monitor real-time weather feeds from the Incheon station for deviations from the 28°C average, particularly if sudden rain or cloud cover reduces peak heating [2]. No external announcements or policy schedules influence this outcome; the dependency is purely meteorological. Automated bots should be configured to fetch the RKSI daily record immediately post-settlement to verify resolution accuracy, ensuring conditional orders execute only when the recorded value matches the selected range.

Sources: 1 · 2

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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 Kalshi Fees. 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 does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.