Highest temperature in Seoul on July 31?

Platform comparison

Market context

The temperature to watch is the day’s peak at Incheon International Airport, not the city centre, so traders should anchor on the airport station’s observed maximum on 31 July and the Wunderground daily-history page at settlement time. At 06:25 UTC, Seoul and north-western South Korea are already in a severe summer pattern, with recent reporting showing daytime highs in the capital area in the mid-to-high 30s Celsius and a strong heatwave context across the region.[4][6][10]

For framing, Seoul’s July climate norm is far lower, with average highs around 29°C and typical late-July maxima in the mid-80s °F range, but historical extremes are much higher: Seoul has reached 38.3°C on 31 July 2018, and the city’s record high is 39.6°C in August 2018.[1][15][18] That matters for programmatic trading because a 0% crowd price can still be mechanically wrong if the market is keyed to an airport reading rather than the city’s official station; a bot should map the resolution source precisely, then pull the intraday max rather than rely on city-level forecasts.

Catalysts are the morning KMA updates, convective cloud cover, sea-breeze effects around Incheon, and any shift in the broader heat advisory picture that changes the afternoon ceiling. Forecast coverage this morning already points to elevated heat across the capital region, with Incheon near 30–31°C and Seoul around 33–37°C in late-July reporting, so traders watching via scripts or conditional orders would typically monitor hourly observations and compare the live airport trend against the published day-ahead forecast path.[4][10][6]

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

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.

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.