Highest temperature in Seoul on June 21?

Platform comparison

Active sub-markets

Market context

Seoul’s daytime heat in June is usually moderate rather than extreme, with typical highs around 26-28°C and a warm-up through the month as humidity rises.[2][3][4] That makes a 0% YES price look like a pure tail view rather than a normal seasonal expectation: this market is tied to the highest temperature at Incheon Intl Airport Station on 21 June, not a city average, so the outcome depends on whether a brief spike reaches an upper temperature band during the settlement window.[1][6]

Comparable June climatology points to a range that is usually well below midsummer peaks, with early June often feeling closer to spring and the monsoon season typically starting later in the month.[1][4][10] On Polymarket, the crowd-implied probability is shown directly, while on Kalshi the same view is usually expressed through contract prices, and on Betfair or Smarkets traders would instead read the market through decimal odds and effective implied probability after fees. That matters here because low-probability weather bands can look cheaper or pricier depending on whether the venue charges commissions, applies maker-taker rebates, or restricts access by jurisdiction and KYC.

The main catalysts are the day’s actual temperature path, cloud cover, wind, and any convective rain or thunderstorms that suppress the afternoon peak. The Korea Meteorological Administration’s short-range forecasts are relevant because it distinguishes daytime highs as the maximum recorded between 9am and 6pm local time, which is the period most likely to determine whether the airport station reaches a higher band.[6] For traders comparing venues, the practical difference is that Polymarket may offer a cleaner probability snapshot, while Betfair and Smarkets can be more sensitive to liquidity and commission, and Kalshi’s availability depends on user access and compliance checks.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in Seoul on June 21? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. Live odds come from the Polymarket order book; the other venues' contract details are maintained manually because their APIs aren't directly comparable. Every CTA routes to Polymarket Alternative, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Is this market available outside the US?

Polymarket Alternative is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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 it cost to trade on Polymarket Alternative?

Zero. Polymarket Alternative routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.