Highest temperature in Seoul on July 21?

Platform comparison

Market context

Seoul’s peak heat on 21 July 2026 will be measured at Incheon International Airport, with the market currently pricing any outcome above 27°C as virtually impossible despite July’s typical highs. The crowd-implied probability of 0% for a “YES” outcome on higher temperatures clashes with the Polymarket frontrunner assigning 86% to exactly 27°C, suggesting a sharp divergence between binary betting lines and range-based odds across platforms.

Historical July data shows Seoul averages a high of 28°C, with 43% of days featuring rain and 80% relative humidity creating a humid but often cooler feel than the thermometer suggests [2]. The 0% market probability for temperatures exceeding 27°C aligns with the 10% chance Polymarket gives to 28°C, indicating traders expect the day to fall just below the monthly average, possibly due to expected precipitation or cloud cover.

Traders should monitor the daily Wunderground history for Incheon (RKSI) as the sole resolution source, watching for real-time updates on cloud density and rainfall intensity that could suppress peak temperatures [1]. No official weather announcements are scheduled before the 12:00 UTC settlement, but sudden shifts in the 43% rain probability could invalidate the current 86% confidence in 27°C, making live humidity and precipitation data the primary catalysts for odds movement.

Sources: 1 · 2

Methodology

We track Highest temperature in Seoul on July 21? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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.

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.