Highest temperature in Seoul (Incheon) on August 9?

Platform comparison

Market context

The latest shift is that short-range forecasts for Seoul continue to point to a hot, humid Sunday with a daytime high around 34–35°C, while showers are now more likely in the afternoon than in the morning. AccuWeather and the Korea Meteorological Administration both show peak temperatures in that band, with the KMA’s 05:00 bulletin calling for generally clear conditions early, increasing cloud later, and scattered afternoon showers in inland parts of Gyeonggi, alongside a forecast high of 34–35°C for today.[2][10]

That keeps the market anchored in a familiar summer pattern: the decisive figure is usually the airport station’s observed maximum, not the broader city forecast, and the spread between forecast highs and the final recorded daily observation can still be a degree or two either way. Recent comparable guidance has been consistently clustered in the low-to-mid 30s Celsius, with BBC-linked reporting earlier this month also noting Seoul highs around 34°C during a run of hot weather, which supports the view that a result above the mid-30s would need an upside surprise from stronger sun and weaker shower interference.[4][7][11]

For traders, the main catalysts are the progression of morning cloud cover, the timing and reach of any convective showers, and whether the airport site stays dry long enough to allow the day’s maximum to be set before afternoon weather limits further warming. The KMA’s updates are the key schedule dependency, and hourly forecasts already show temperatures climbing through late morning into early afternoon before shower risk increases, which makes the noon-to-afternoon window the one most likely to decide the final observed high.[9][10]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

UK Frequently Asked Questions

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.