Highest temperature in Seoul on June 21?

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Market context

The reading that matters is the *highest temperature at Incheon International Airport Station*, which is the settlement source for this market, not the city-wide forecast headline. For late June in Seoul and the surrounding capital region, the climate normally supports afternoon highs in the high 20s Celsius, with June highs typically rising through the month and rarely exceeding the upper 20s to around 30°C on a normal day.[2] That means a 0% implied chance for the “YES” side is a statement about market pricing, not about the physical possibility of a warm or hot day.

The best historical frame is that South Korea can produce very high summer temperatures, but the odds are usually driven by the exact airport reading, cloud cover, sea-breeze effects and timing of the daily maximum. Weather Underground has documented extreme Korean heat well above 40°C in national records, while broader regional climate reporting notes that recent summers in South Korea have been unusually warm and prone to record-breaking heat.[3][4] For a market like this, the book often tightens only when funding is easy and traders can move quickly; deposits and exits through lower-friction rails such as Klarna, SEPA or USDC tend to matter because they affect how much capital can be deployed into a short-dated weather contract.

Traders should watch the morning setup over the airport and the wider north-western Korean Peninsula: clear skies, weak winds and strong inland advection raise the odds of a higher afternoon print, while cloud, rain bands or a sea breeze cap the ceiling. The market’s depth can also shift sharply if fresh model runs or local forecasts point towards a hotter-than-normal peak, because weather contracts are most sensitive to late revisions before the settlement window closes. If payment rails are slow or costly, that usually shows up as thinner books and wider spreads rather than a change in the meteorology itself.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Seoul on June 21? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Klarna UK, which mirrors the Polymarket order book at 0% fees. 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.

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?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket Klarna UK triggers a quick verification flow that finishes in 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.