Highest temperature in Seoul on July 23?

Platform comparison

Market context

The key event is the day’s maximum temperature at Incheon International Airport, which is the settlement source for this market, so the trade is really about whether the afternoon peak lands inside a narrow Celsius band rather than the headline city forecast. Polymarket currently prices **27°C** as the frontrunner at **49%**, with **28°C** next at **30%**[1]. That distribution is already a useful read-through for a market showing **0% YES** elsewhere: on a weather day where July norms in South Korea are near **30°C** highs and about **23°C** lows, the market is effectively pricing a modest warm day rather than an extreme heat spike[2].

For historical framing, late-July Seoul-area temperatures often cluster around the high-20s to low-30s, so the most relevant comparison is not whether it will be hot, but whether cloud cover, rainfall or sea-breeze effects cap the airport reading below the hotter inland expectation[2]. On platforms, the same event can look different: Polymarket shows outcome bands with implied probabilities, while Kalshi typically uses binary contracts and platform-specific fees, and Betfair or Smarkets would expose the same weather view through decimal odds and exchange commission rather than a direct probability label. That matters here because a 27°C or 28°C landing can be translated into very different quoted prices depending on whether the venue is a market maker venue, a US-regulated venue, or an exchange with broader KYC access.

The main catalysts are the final local forecast updates, any shift in precipitation timing, and the day’s actual noon-to-afternoon heating profile at the airport. Because the market settles on the highest reading recorded on the day at Incheon International Airport, late sunshine, passing showers, or persistent humidity can all matter more than the morning temperature alone. Traders should also watch for any operational or data-source specifics from the resolution feed, since the contract references Wunderground’s daily history page for RKSI rather than a citywide Seoul station, which can diverge from the broader metropolitan forecast[1].

Sources: 1 · 2

Methodology

We read Highest temperature in Seoul on July 23? 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

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.

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.

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.

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 UK has a different geo footprint and routes to Polymarket's order book at 0% fees.