Highest temperature in Seoul on July 5?

Platform comparison

Market context

On 5 July 2026, the Incheon International Airport Station will record its peak temperature for the day, a single data point that determines the outcome of a prediction market currently implying zero probability for any YES result. This event is not abstract; it is a concrete meteorological measurement that will be captured by Wunderground and resolved against predefined Celsius ranges, with the settlement window closing at 12:00 UTC on the settlement date.

Historical context frames this 0% probability as highly questionable given South Korea’s recent thermal trajectory. July 2025 was the second-hottest July on record, with a nationwide average of 27.1°C, just behind the 1994 peak of 27.7°C[1]. Seoul itself reached 37.7°C in early July 2025, the highest such temperature in 117 years of records[7]. Furthermore, the country endured its hottest summer since data collection began in 1973, with average summer temperatures hitting 25.0°C[3]. Daily highs in Seoul during July typically range from 81°F to 85°F, rarely falling below 74°F or exceeding 91°F[2], suggesting that a temperature falling into a lower range is statistically improbable.

A power-user approaching this market programmatically would monitor real-time weather feeds from Wunderground and cross-reference them with the Korea Meteorological Administration’s daily bulletins for early July anomalies. The primary catalyst is the persistence of the tropical night phenomenon, which saw Seoul experience its longest stretch of such nights in 117 years during July 2025[8]. Traders should watch for any official announcements regarding heatwave advisories or extreme weather schedules, as the 2.5°C deviation above the 1991–2020 average in recent months indicates a systemic shift toward higher baselines[5]. The resolution source is strictly the highest temperature recorded for all times on that day, making continuous monitoring essential rather than relying on single daily snapshots.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Seoul on July 5? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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'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 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.