Highest temperature in Seoul on July 21?

Platform comparison

Market context

On 21 July 2026, the real-world event determining this market’s outcome is the highest air temperature recorded at Incheon International Airport in Seoul, measured in degrees Celsius. A YES share in this market means you believe the peak temperature will fall within the specific range offered; a NO share means you expect it to fall outside that range. Currently, the crowd assigns a 0% probability to the YES outcome, suggesting traders overwhelmingly doubt the temperature will reach the proposed threshold.

Historical July data for Seoul shows average highs of 28°C, with humidity often reaching 80% and rain occurring on 43% of days [1]. While extreme heatwaves can push temperatures above 35°C, such events are uncommon and typically linked to specific atmospheric conditions like stagnant high-pressure systems. The current 0% implied probability aligns with the statistical norm that Seoul rarely experiences record-breaking heat in mid-July, making the target range appear unrealistically high based on past patterns.

Traders should monitor daily weather forecasts from the Korea Meteorological Administration and real-time updates on Wunderground, the official resolution source for this market. Key catalysts include announcements of heatwave advisories, shifts in monsoon activity, and any sudden changes in regional wind patterns that could trap heat near the airport. As the settlement window closes at 12:00 UTC on 21 July, the final temperature reading will be locked in from the Incheon station’s hourly records, leaving no room for revision once the day ends.

Sources: 1

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 Market UK. 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.

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.