Highest temperature in Seoul on July 17?

Platform comparison

Market context

Seoul is set to face its peak summer heat on 17 July 2026, with the Incheon International Airport station serving as the official benchmark for the day’s highest temperature. The prediction market currently assigns a 0% probability to the “YES” outcome, implying near-certainty that the temperature will fall outside the specific range being wagered on, though the frontrunner on Polymarket is 31°C at 76% probability, with 32°C or higher trailing at 22% [1]. This stark divergence between the 0% crowd-implied probability and the 76% market favourite for 31°C suggests a potential misalignment in how traders interpret the settlement conditions or the specific temperature range in question.

Historically, Seoul has experienced extreme July heat, including the hottest July since 1908 recorded in 2025, when a prolonged heatwave persisted until at least 16 July [2]. Comparable cases from recent years show that temperatures frequently reach 31–33°C during mid-July, making the 31°C outcome statistically plausible and aligning with the Polymarket frontrunner. The 0% implied probability on the “YES” side may reflect confusion over the exact range definition rather than a genuine belief that temperatures will be unusually low, given the region’s consistent summer patterns.

Traders should monitor real-time updates from Wunderground, the official resolution source, and watch for any sudden shifts in weather forecasts from Korean meteorological agencies as the settlement window closes at 12:00 UTC on 17 July. No major announcements or scheduled events are expected to alter the temperature directly, but rapid changes in cloud cover or wind patterns could influence the final reading. The key dependency remains the accuracy of the Wunderground data for the Incheon station, which will determine the market’s resolution without ambiguity.

Sources: 1 · 2

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 PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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 PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.