Highest temperature in Tokyo on August 17?

Platform comparison

Market context

Tokyo's maximum temperature on 17 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 settlement window closes at midday UTC on that date, meaning traders must account for the full diurnal cycle and any measurement lag between local observation and platform publication.

August in Tokyo typically peaks between 32–35°C, with occasional excursions above 36°C during heat waves. Historical August 17th maxima at Haneda show a range of 29–35°C over the past two decades, with the 0% crowd probability suggesting the market's upper brackets are currently unpriced. Traders evaluating this programmatically should note that Haneda's coastal location moderates extremes compared to central Tokyo; sea-breeze effects and airport microclimates create systematic deviations from broader city forecasts. Automated systems pulling from Weather Underground's API will need to parse the Daily Observations table specifically, as the Day High & Low summary section can diverge by 1–2°C.

Catalysts include the Japan Meteorological Agency's seasonal forecasts (typically issued in late July) and real-time atmospheric patterns in mid-August. El Niño or La Niña phases influence Pacific summer circulation; the 2024 summer saw above-normal heat across eastern Japan. Traders building conditional orders should monitor upper-air ridge positioning and tropical moisture advection in the week preceding 17 August, as these drive whether conditions favour the 32–34°C or 35°C+ brackets.

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.

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 Kalshi Fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

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