Highest temperature in Tokyo on August 20?

Platform comparison

Market context

On 20 August 2026, Tokyo Haneda Airport will record a daily maximum temperature in Celsius, with traders on Polymarket currently pricing all temperature ranges at 0% probability across the board. This suggests either minimal liquidity in the contract or genuine uncertainty about which specific range will contain the day's peak reading. The market's settlement hinges on Weather Underground's Daily Observations table rather than the summary high-low figures, a distinction that occasionally matters when automated station equipment logs micro-fluctuations differently from human-reviewed summaries.

Tokyo's August climate presents a consistent baseline for comparison. Historical data shows late-August highs typically cluster between 32–35°C, with extreme readings above 37°C occurring roughly once per decade during particularly intense heatwaves. The summer of 2023 saw Tokyo record 37.1°C on 15 August, whilst 2022 peaked at 35.5°C in the same window. These precedents suggest the most probable outcome falls within the 33–36°C band, though climate patterns have shifted measurably over the past fifteen years, with heat records becoming more frequent.

Traders monitoring this contract should track Japan Meteorological Agency forecasts released in early August 2026, which typically provide reliable ten-day outlooks. Pacific typhoon activity during mid-August can suppress temperatures significantly, whilst high-pressure systems from the continent drive readings upward. Any major weather systems affecting East Asia in the fortnight before settlement will reshape the probability distribution. USDC liquidity on Polygon remains the constraint; early position-taking at current 0% pricing reflects the contract's nascent stage rather than genuine confidence in any particular outcome.

Methodology

We track Highest temperature in Tokyo on August 20? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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%.