Highest temperature in Seoul on June 30?

Platform comparison

Market context

The underlying event is the daily peak temperature at Incheon International Airport on 30 June 2026, a figure that will determine the settlement of a weather prediction contract. Current crowd-implied probability for the “YES” outcome sits at 0%, suggesting the market believes the temperature will not reach the specified threshold. This stands in stark contrast to historical patterns where Seoul routinely experiences highs between 77°F and 81°F in June, rarely dipping below 68°F or exceeding 87°F[1]. The region has seen record-breaking June heat in recent years, including South Korea’s hottest average June temperature since 1973, recorded at 22.9°C in 2025[4]. In 2018, Seoul itself hit 39.6°C, surpassing its prior record of 38.4°C[6], while Hongcheon later set an all-time national record of 41.0°C in 2023[2]. These precedents frame the 0% probability as unusually conservative, especially given the trend of intensifying summer heat across the country.

Traders should monitor real-time weather updates from Wunderground, the official resolution source, particularly as the settlement window closes at 12:00 UTC on 30 June. Any sudden shifts in cloud cover, wind patterns, or humidity could alter the peak temperature significantly. Recent reports indicate South Korea experienced record-breaking June heat in 59 cities, with 30 June marking the hottest day since modern records began in 1904[7]. Analysts note that such extreme conditions are becoming more frequent, challenging the market’s current dismissal of higher temperature outcomes. While sportsbooks may offer more balanced odds on similar weather contracts, the prediction market’s 0% implied probability appears disconnected from both historical data and current climatic trends. This divergence highlights a meaningful gap between market sentiment and empirical reality, offering a potential arbitrage opportunity for informed participants.

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

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 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.

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.