Highest temperature in Seoul on July 4?

Platform comparison

Market context

The underlying event is a single day’s peak heat at Incheon International Airport on 4 July 2026, with the market asking whether that high will land exactly in the 29°C bracket. Historical early-July highs in Seoul typically cluster between 27°C and 31°C, making 29°C the statistical centre but not a majority outcome; six other temperature ranges share the remaining probability, so no single bracket commands consensus. Recent records show Seoul hitting 37.7°C in early July 2023—the highest in 117 years—while 2025 saw 35.8°C in the capital, confirming that the window is genuinely wide and volatile rather than tightly bound to the mean[1][2][7].

Current crowd-implied probability sits at 0% YES for the 29°C hit, yet the broader market on similar platforms trades NO at 66% implied probability, with the 29°C bracket leading only at 30.5% because it sits centrally in the historical range[1]. The consensus leans heavily toward NO, viewing any deviation from 29°C as more likely, but value may sit contrarian on a narrow 28–30°C swing if the Korea Meteorological Administration releases a cooler-than-expected forecast before noon KST. Traders should watch the KMA’s daily 06:00 UTC update and Wunderground’s real-time feed for Incheon, as thin volume below $1M means prices can shift sharply on any new temperature data[1]. No major weather announcements are scheduled, but the dependency on the 06:00 UTC forecast remains the critical catalyst for this resolution window.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in Seoul on July 4? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Who Will Win, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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 Who Will Win. 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.

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.

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.