Highest temperature in Tokyo on August 20?

Platform comparison

Market context

Tokyo's peak temperature on 20 August 2026 will be measured at Haneda Airport Station using Weather Underground's Daily Observations table, with settlement occurring at midday UTC on that date. The current crowd assessment sits at 0% probability, suggesting traders view this outcome as either impossible or so unlikely that no meaningful odds exist for any specific temperature band.

August temperatures at Tokyo Haneda typically range between 28–34°C, with historical data from the past two decades showing that extreme heat events above 37°C occur sporadically but remain within the realm of possibility during peak summer months. The 2010 heatwave saw Tokyo record 39.9°C, and more recently, August 2023 produced several days exceeding 36°C. The zero probability reading likely reflects either a technical issue with market setup, a misunderstanding of the resolution criteria, or traders' confidence that no extreme outlier scenario will materialise in this particular year.

The key dependency for this market is the accuracy and availability of Haneda Airport Station data on Weather Underground's Daily Observations table—the specified primary source. Traders should verify that the station maintains consistent reporting and that no data gaps occur on the settlement date itself. Japan Meteorological Agency forecasts and any issued heat warnings in late July or early August 2026 will signal whether atmospheric conditions are trending toward unusual extremes. The distinction between the Daily Observations table and the Day High & Low summary section matters operationally; discrepancies between these sources have historically caused resolution disputes on weather markets.

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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 Who Will Win 2026. 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.

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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.