Highest temperature in Seoul on July 20?

Platform comparison

Market context

Seoul faces its peak summer heat on 20 July 2026, with the market betting on the highest temperature recorded at Incheon International Airport. The crowd-implied probability of a specific outcome sits at 0% YES, suggesting traders view the proposed temperature range as virtually impossible given typical July conditions. Historical data shows Seoul’s average July high reaches 28°C, while the wettest month of the year brings a 43% chance of daily precipitation, often moderating extreme spikes through cloud cover and rain [1].

Comparable cases from recent summers indicate that temperatures exceeding 35°C are rare but not unheard of during heatwaves, yet the 0% probability implies the market expects conditions well below such extremes. Traders should monitor the Korea Meteorological Administration’s daily heatwave advisories and real-time Wunderground readings for the Incheon station, as these serve as the official resolution source. Any sudden shift in monsoon patterns or an unexpected heat dome could alter the trajectory, though current forecasts align with the consensus that the target range is unattainable.

The divergence between sportsbook lines and prediction-market odds highlights a stark disagreement on risk assessment, with traditional bookmakers likely pricing in a small chance of outlier heat while Polymarket traders dismiss it entirely. Analyst consensus leans heavily toward the 28–32°C band, making the 0% YES contract a clear mismatch with seasonal norms. For those comparing platforms, Kalshi’s tighter spreads may offer better value if the market corrects, but the current pricing reflects a firm belief in moderate summer weather.

Sources: 1

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi vs Polymarket, which mirrors the Polymarket order book directly.

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.

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.

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.