Highest temperature in Seoul (Incheon) on August 9?

Platform comparison

Market context

The key event is whether the highest observed temperature at Incheon Intl Airport Station on 9 August reaches a band above the market’s current 0% implied probability, which is far below recent Seoul-area conditions. Reuters reported Seoul was forecast to hit **39°C** on 6 August amid an extreme heatwave, while local coverage said Seoul touched **39.9°C** in Yongsan on 7 August, showing that the upper tail of the distribution has been very warm this week.[8][15]

For context, August in Seoul normally runs much cooler than this spell, with typical highs around **30–31°C** and highs in the low 90s Fahrenheit on forecast pages for early August.[16][12] That makes the current “yes” side look cheap only if traders think the airport station will stay well below the city’s recent peaks; on Polymarket, the quoted figure is an implied probability, whereas Betfair and Smarkets would typically express the same view through decimal prices and charge commission on winnings, so cross-platform comparison is not one-to-one. KYC and access also vary: Polymarket access and settlement conventions differ from UK-facing betting exchanges, which can change who is able to trade the same weather view.

The main catalysts are the Korea Meteorological Administration short-range outlooks, any overnight shift in the heat dome, and the first published daily observations from Incheon Airport, because the market settles on the daily observations table rather than a headline summary.[6][3] Reuters noted the heatwave was expected to peak over Seoul around 6 August before easing later in the week, so traders should watch whether that moderation reaches the airport station in time for the 9 August reading.[8]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in Seoul (Incheon) on August 9? 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

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.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Robinhood Prediction Markets 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.