Highest temperature in Seoul on July 4?

Platform comparison

Market context

The real-world event hinges on the highest temperature recorded at Incheon International Airport on 4 July 2026, with the market currently pricing a 29°C hit at zero probability. Historical data from the Korea Meteorological Administration shows early July highs in Seoul typically cluster between 27°C and 31°C, while Weather Spark notes daily highs rarely fall below 74°F or exceed 91°F[1][5]. Recent records are particularly volatile; South Korea endured its second-hottest July since 1973 in 2025, averaging 27.1°C, and Seoul reached 37.7°C in early July, the highest such reading in 117 years[3][4]. This wide variance means no single temperature bracket commands majority support, with the 29°C range leading only because it sits at the historical centre, yet traders still view it as a minority outcome with roughly a one-in-three chance[1].

A power-user approaching this programmatically must monitor the Korea Meteorological Administration’s daily forecast releases and Wunderground’s real-time station updates for Incheon, as the resolution source is explicitly tied to their highest recorded value for the day[1][2]. The primary catalyst is the immediate weather pattern over the Korean peninsula, specifically the presence or absence of a tropical air mass or monsoon rain, which can swing temperatures by several degrees within hours. Recent news from Anadolu Ajansı highlights that extreme heat events are becoming more frequent, with Seoul hitting record highs that defy seasonal averages, suggesting that relying solely on historical averages is insufficient for accurate modelling[4]. Traders should also watch for any sudden shifts in wind direction or humidity levels, as these dependencies directly influence the peak temperature recorded at the airport station before the settlement window closes at noon KST.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Seoul on July 4? 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

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

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.

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.