Highest temperature in Seoul on July 20?

Platform comparison

Market context

Seoul faces its peak summer heat on 20 July 2026, with the market tracking the highest temperature recorded at Incheon International Airport. Historical data shows July averages in Seoul typically range from 21°C to 28°C, making extreme highs above 35°C rare but possible during intense heatwaves [1]. The current 0% implied probability for any specific high-temperature range suggests the crowd expects conditions to remain within standard seasonal bounds, though this differs sharply from platforms like Kalshi, which often display decimal odds rather than raw probabilities, potentially obscuring the true risk for casual traders.

Comparing books reveals distinct structural divergings: Polymarket’s fee structure and lack of KYC contrast with Betfair’s deeper liquidity and Smarkets’ lower commission rates, which can materially alter payout expectations on weather events. While Kalshi requires strict identity verification and operates under US regulatory frameworks, Polymarket’s global access allows traders in Asia to participate without intermediaries, a key advantage for regional weather markets. Historical heatwaves in Seoul, such as the 2018 event reaching 39°C, provide a benchmark, yet the current pricing implies no such anomaly is anticipated, highlighting how platform-specific liquidity can skew perceived risk.

Traders should monitor the Korea Meteorological Administration’s daily forecasts and Wunderground’s real-time updates for Incheon, as sudden shifts in monsoon patterns or urban heat retention could invalidate current pricing. Recent climate reports indicate increasing volatility in East Asian summer temperatures, though no specific announcement for 20 July has been issued yet [1]. The settlement window ending at 12:00 UTC ensures resolution aligns with the full day’s data, but traders on platforms with delayed feeds may face execution risks compared to those using Polymarket’s near-instant updates.

Sources: 1

Methodology

This page compares Highest temperature in Seoul on July 20? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi Alternative, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Kalshi Alternative has a different geo footprint and routes to Polymarket's order book at 0% fees.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.