Highest temperature in Seoul on July 21?

Platform comparison

Market context

Seoul’s highest temperature on 21 July 2026 at Incheon International Airport is the real-world event determining this contract’s outcome, with the market currently pricing a 0% chance for any YES resolution outside the defined temperature ranges. On Polymarket, traders use USDC on Polygon to buy conditional tokens, and the frontrunner outcome is 27°C at 86% implied probability, while 28°C sits at 10% [1]. This pricing reflects the crowd’s view that extreme heat above typical July highs is unlikely, aligning with historical patterns where Seoul’s average July high is 28°C (83°F) [2].

Historical data shows Seoul in July is very humid with 80% relative humidity and a 43% daily rain chance, which often moderates peak temperatures [2]. The 86% probability assigned to 27°C suggests traders expect conditions near the average rather than record-breaking heat, consistent with past years where rain and humidity prevent sustained extremes. The 10% probability for 28°C indicates a small but non-zero chance of hitting the typical average high, while outcomes above 28°C are effectively priced out.

Traders should monitor daily weather updates from Wunderground for the Incheon station, as the market resolves solely on its recorded highest temperature for the day [1]. Key catalysts include any sudden shifts in precipitation forecasts or humidity levels, which could push temperatures below 27°C, or unexpected heatwaves that might breach 28°C. Since settlement ends at 12:00 UTC on 21 July 2026, real-time data from the official resolution source will be the final determinant, with no room for post-event adjustments.

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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 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.

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.