Highest temperature in Seoul on June 30?

Platform comparison

Market context

The real-world event is the highest temperature recorded on 30 June 2026 at Incheon International Airport, measured in degrees Celsius and resolved via Wunderground. Seoul’s June climate typically sees daily highs rising from 77°F to 81°F, rarely dipping below 68°F or exceeding 87°F[1]. Historical data shows South Korea hit an all-time peak of 41.0°C in Hongcheon, while Seoul itself reached 39.6°C in 2018[2][6]. Recent years confirm a warming trend: June 2025 was the hottest ever since 1973, with 22.9°C average, and 59 cities recorded record-breaking heat[4][7]. Given this pattern, a 0% YES probability implies the market expects temperatures far below the threshold for a “high” outcome, which contradicts recent climatic behaviour unless the threshold is exceptionally high.

A programmatic trader would monitor Wunderground’s live feed for Incheon on 30 June, cross-referencing with AccuWeather’s forecast of 85°–91°F highs for June 2026[8]. Key catalysts include the Korea Meteorological Administration’s daily heat advisories and any sudden shifts in the East Asian monsoon, which could suppress temperatures. Recent news from Yonhap confirms South Korea’s June 2025 average was 0.2°C higher than 2024, reinforcing the trend of escalating heat[4]. Traders should also watch for cloud cover anomalies, as June’s shortwave solar energy in Seoul is gradually decreasing, falling from 6.5 kWh to 6.0 kWh[1]. If Wunderground reports a spike above 35°C, the market’s 0% probability would be instantly invalidated, suggesting a mispricing rooted in outdated assumptions rather than current data.

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

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

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.