Highest temperature in Seoul on July 5?

Platform comparison

Market context

The underlying event is the peak daytime heat recorded at Incheon International Airport on 5 July 2026, a date that historically sits within Seoul’s most intense summer window. Current crowd-implied probability of 0% YES suggests the market expects temperatures to fall below the highest threshold, yet this figure clashes with recent climatic trends. Since modern records began in 1973, Korea’s hottest July occurred in 1994 with an average of 27.7°C, while July 2025 marked the second-hottest on record at 27.1°C nationwide[1]. Incheon and Seoul typically see daily highs rising from 81°F to 85°F in July, rarely dipping below 74°F or exceeding 91°F[2]. The all-time national heat record of 41.0°C was set in Hongcheon, but Seoul itself reached 37.7°C in early July 2025, the highest such reading in 117 years[6]. These precedents indicate that a 0% probability may be an overcorrection, as extreme heat is not merely possible but increasingly recurrent.

A power-user evaluating this market programmatically would monitor real-time Wunderground feeds for Incheon, cross-referencing with Korea Meteorological Administration advisories on high-pressure systems from the North Pacific. The primary catalyst is the intensification of the North Pacific high-pressure system, which drives hot, humid air into the region and can push temperatures toward 35°C or higher[8]. Traders should watch for official announcements regarding tropical night durations, as July 2025 saw the longest stretch of such nights in Seoul for 117 years, indicating heat that lingers well into the night[7]. Recent data confirms South Korea endured record-breaking summer heat in August 2025, with average temperatures 2.9°C above the 1991–2020 baseline[4]. Programmatically, one would set conditional orders triggered by Wunderground spikes above 36°C, using the gear icon to toggle between Fahrenheit and Celsius for precision. The settlement window ends 12:00 UTC on 5 July 2026, requiring automated scripts to capture the peak before that deadline.

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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

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.