Highest temperature in Tokyo on August 8?

Platform comparison

Market context

Tokyo’s afternoon high on 8 August will be set by the maximum value logged at Haneda Airport Station in Weather Underground’s Daily Observations table, so the practical task is to watch the intraday prints rather than the summary panel. At 9:39 AM JST, Weather Underground showed 92°F and partly cloudy conditions, while nearby services pointed to a forecast near 94°F for the day, which already places the market firmly in a hot-weather band rather than a borderline case.[4][2]

The current 0% crowd-implied probability looks consistent with a market that still has most of the day to run and where the relevant number is the day’s *peak*, not the morning reading. August climatology in Tokyo supports that framing: long-run sources put typical highs around 30–31°C, with August regularly reaching 33–35°C on hotter days, and WeatherSpark notes 8 August sits at the muggiest point of the month.[11][14][13] For programmatic monitoring, a trader would usually poll the Daily Observations row at intervals, compare successive temperature updates, and map the running maximum into the market’s settlement bands.

What matters next is whether local cloud cover, sea-breeze effects, or a late-afternoon shower cap the peak before the settlement cut-off. The immediate dependencies are the forecast trajectory through midday, any rapid rise after late morning, and whether the station’s next observation jumps enough to move the reading into a higher band; current hourly guidance still leans into low-90s Fahrenheit through early afternoon.[2][4] If you are automating this, the useful trigger is not a single forecast source but a threshold-based alert on the observed maximum at Haneda, since that is the figure the market explicitly uses for resolution.[4]

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

UK Frequently Asked Questions

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Review UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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%.