Highest temperature in Seoul on July 20?

Platform comparison

Market context

Seoul faces its peak summer heat on 20 July 2026, with the Incheon International Airport station set to record the day’s highest temperature in degrees Celsius. Short-term forecasts currently point to a high near 28°C, aligning with the city’s typical July average of 28°C for daytime highs[2]. The prediction market “Highest temperature in Seoul on July 20?” shows a 0% crowd-implied probability for the YES outcome, suggesting traders believe the temperature will fall outside the specified range, despite forecasts clustering tightly between 26–29°C[1].

Historically, Seoul’s July temperatures rarely deviate far from the 28°C average, with precipitation chances at 43% often moderating extreme heat[2]. Comparable cases from recent years show highs typically landing within the 26–30°C band, making a 0% YES probability unusual unless the market’s range is set below 26°C or above 29°C. This divergence between forecast consensus and market odds mirrors discrepancies seen when sportsbook lines on weather derivatives lag behind real-time meteorological updates.

Traders should monitor hourly updates from Wunderground, the official resolution source, and watch for any revised short-term forecasts as the settlement window closes at 12:00 UTC on 20 July 2026[1]. No major weather announcements are scheduled, but sudden shifts in cloud cover or precipitation could alter the final reading. The tight clustering of market odds around 26–29°C suggests limited volatility, yet the 0% YES probability remains an outlier compared to the forecasted 28°C high[1][2].

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 PolyGram. 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.

Do I need to KYC for this market?

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

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.