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. The current crowd-implied probability of 0% for the YES outcome suggests traders expect temperatures to fall outside the specific range offered, likely due to the city’s typical July highs averaging 28°C. Historical data shows Seoul’s July temperatures usually range between 21°C and 28°C, making extreme spikes above 35°C uncommon but not impossible during monsoon-related heatwaves [1].

Comparable cases from recent years show that while Seoul regularly hits 30–32°C in late July, temperatures exceeding 35°C are rare and often linked to specific atmospheric conditions like stagnant high-pressure systems. Traders should monitor the Korea Meteorological Administration’s daily forecasts and any announcements regarding heatwave advisories, which can signal a shift toward extreme temperatures. A recent report from Yonhap News noted that South Korea is experiencing increasingly intense summer heat due to climate change, with 2024 and 2025 seeing record-breaking temperatures in the capital region.

On platform mechanics, Polymarket displays outcomes as decimal odds while Kalshi and Betfair use implied probability, affecting how traders interpret the 0% figure. Fee structures also diverge: Polymarket charges a flat 2% fee on profits, whereas Kalshi applies variable fees based on liquidity and Betfair uses a commission model. KYC requirements further distinguish these books, with Kalshi enforcing strict US identity verification while Polymarket and Smarkets offer more accessible entry for international users, impacting who can trade this weather event.

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 UK, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). On-chain settlement clears in minutes — the fastest payout path of the four.

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.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.

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.