Highest temperature in Seoul on July 18?

Platform comparison

Market context

Seoul's peak temperature on 18 July 2026 will be measured at Incheon International Airport Station, the official reference point for the metropolitan area. The settlement mechanism relies on historical weather data from Weather Underground, requiring traders to verify the exact daily maximum rather than estimate from forecasts. This market resolves based on recorded observation, not prediction models, making it a direct test of what actually occurred rather than what meteorologists anticipated.

July in Seoul typically sees daily highs between 28–32°C, though heat waves can push readings above 35°C. The 0% crowd probability suggests either extreme confidence in a specific temperature band or insufficient liquidity across the range options. Historical context matters here: Seoul experienced a 39.6°C peak in August 2018 during an exceptional heat event, but mid-July readings rarely exceed 34°C in typical years. Traders automating this market would benefit from integrating historical daily maxima from the Incheon station directly—Weather Underground's API allows programmatic access to both historical records and settlement verification.

The critical variable is whether an early-season heat dome affects East Asia in mid-July 2026. South Korea's meteorological agency typically issues heat warnings 3–5 days in advance when temperatures are forecast to exceed 33°C. Traders monitoring the Korea Meteorological Administration's official forecasts and any issued advisories around 13–15 July would have actionable signals. The settlement window closes at noon UTC on 18 July, meaning traders have until the final observation is recorded at Incheon to adjust positions based on real-time temperature data.

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.

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?

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