Highest temperature in Tokyo on August 15?

Platform comparison

Market context

Tokyo's peak temperature on 15 August 2026 will be measured at Haneda Airport Station and recorded in Weather Underground's Daily Observations table, with resolution tied to that specific data source rather than summary figures. The distinction matters for programmatic resolution: traders integrating this market into conditional order logic or automated monitoring systems must query the correct WU endpoint to avoid mismatches between headline highs and granular observation records.

August temperatures in Tokyo typically range from 28–35°C, with the 15th falling within peak summer heat. Historical data from the Japan Meteorological Agency shows mid-August averages around 31–32°C at Haneda, though extreme heat events have pushed daily highs above 37°C in recent years. The 0% crowd probability suggests the market's range brackets may sit above realistic expectations for that date, or traders are treating this as a calibration exercise rather than a genuine forecast. Comparable August markets in previous years have resolved across the full temperature spectrum, indicating genuine uncertainty rather than systematic bias.

Traders should monitor Japan Meteorological Agency forecasts released in early August and track any heat wave advisories issued by mid-month. Pacific typhoon activity in late July can suppress August temperatures, whilst high-pressure systems anchored over the region drive sustained heat. Real-time integration with WU's API allows automated position management if forecasts shift materially, though the settlement window's specificity to a single day and single station location means hedging through broader Japanese weather derivatives offers limited protection.

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

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%.