Highest temperature in Seoul (Incheon) on August 18?

Platform comparison

Market context

Seoul's maximum temperature on 18 August 2026 will be measured at Incheon International Airport Station and reported through Weather Underground's Daily Observations table, with resolution contingent on that source rather than summary figures. The market currently shows 0% implied probability across all temperature bands, suggesting either thin liquidity or a technical issue in crowd pricing, as August temperatures in Seoul are historically well-documented and predictable within reasonable ranges.

Historical August data from Incheon shows consistent patterns: the station typically records highs between 28–32°C during mid-August, with extreme readings above 34°C occurring roughly once per decade during heat waves. The 2018 Korean heat wave pushed temperatures to 39°C in Seoul proper, though airport readings tend slightly lower due to coastal influence. This historical distribution should anchor any rational probability assessment; the current 0% reading across all bands reflects either market dysfunction or insufficient trader participation rather than genuine uncertainty about whether measurable temperature will occur.

Traders monitoring this market should note the divergence in how major platforms handle weather resolution. Kalshi's strict adherence to Weather Underground's Daily Observations table differs from Betfair's historical reliance on multiple meteorological sources, whilst Smarkets typically requires explicit data-feed specifications pre-launch. Polymarket's fee structure (2% maker, 2% taker) versus Kalshi's flat 2% exit fee creates different breakeven thresholds for arbitrage between platforms. The settlement window closes 18 August 2026 at 12:00 UTC, which falls mid-morning Korean time, potentially before the day's peak temperature is recorded—a critical detail affecting late-day trading strategy.

Methodology

We read Highest temperature in Seoul (Incheon) on August 18? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live mid is the canonical probability; the side-by-side columns benchmark fees, KYC, settlement currency and deposit rails so you can choose the venue that fits your jurisdiction and trade size.

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.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Kalshi Alternative offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.