Highest temperature in Seoul on July 31?

Platform comparison

Market context

Seoul woke up warm rather than cool, with early readings around 27.7°C in the capital and nearby Incheon before sunrise, and forecasters were still pointing to a hot afternoon rather than a sharp break in the heat. Local reporting on 31 July said daytime highs across major regions were expected to run from about 31°C in Incheon to 33°C in Seoul, which is comfortably above the late-July average but not yet in the extreme territory seen during Korea’s biggest heat episodes.[3][10][14]

That backdrop matters because the market is tied to the highest temperature at Incheon Intl Airport Station, not the city proper. July highs in Seoul typically sit in the mid-20s to mid-30s Celsius, and recent years have shown that late-July heat can still produce much higher spikes: Seoul reached 38.3°C on 31 July 2018, while 2025 brought a run of record tropical nights and persistent daytime heat across the peninsula.[2][4][8][11] Against that history, a 0% crowd price implies the market is treating an above-average, but not record-breaking, airport reading as the base case.

The key catalyst is the day’s temperature progression at the airport through the afternoon, when Korean highs usually peak, alongside any changes in cloud cover, sea breeze, or rainfall that could cap the maximum. Traders should watch the Korea Meteorological Administration’s short-term updates and local airport weather observations, because the resolution depends on the single highest reading before the settlement window closes rather than the broader Seoul forecast.[18][20]

Sources: 1 · 2 · 3 · 4 · 5

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 Prediction Today. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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.

Do I need to KYC for this market?

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