Highest temperature in Seoul (Incheon) on August 3?

Platform comparison

Market context

The real-world event is whether the **Incheon Intl Airport Station** posts a high enough temperature on 3 August for the reading to land in the winning band, and the market’s **0% YES** crowd price leaves the favourite firmly on the “no” side. On current public forecasts, Seoul is broadly seen around the mid-to-high 30s Celsius, while Incheon is lower, with one Korean outlet putting Incheon at **34°C** and Seoul at **37°C** for the day[3]. That gap matters because the settlement source is the airport station reading, not the city centre, so the bar for an upside surprise is a genuine local hot spot rather than a general heatwave headline[3][8].

Historically, August in Seoul is hot, humid and often unsettled, but the comparable case framing here is that Incheon usually runs a touch cooler than inland Seoul, especially when sea influence or afternoon cloud caps the peak[2][18]. That makes the current 0% implied probability look like a strong favourite to stay “no” unless the airport site catches unusually intense sun and dry downslope flow. The value spot, if any, is on contrarian upside bands only if the market has over-anchored to a coastal location behaving like the capital proper; otherwise, consensus is clearly aligned with a lower Incheon high than the city headline suggests[3][8].

For traders, the key catalyst is the short-range forecast and any same-morning KMA updates on heatwave advisories, wind direction and cloud cover, because easterly flow is being cited as a factor that can push western areas hotter, while showers are only forecast for other regions later in the day[1][3]. SBS says Seoul is under a heatwave warning and temperatures could climb to 37°C, with skies mostly clear, which supports the broader heat narrative but does not guarantee the airport will match it[1]. The practical watchpoint is whether Incheon remains under a slightly cooler marine regime while inland stations surge, or whether a late-day spike lifts the airport reading into a higher range[3][8].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.