Highest temperature in Tokyo on August 20?

Platform comparison

Market context

The market seeks the highest temperature recorded at Tokyo Haneda Airport on 20 August 2026, with settlement based on Weather Underground's Daily Observations table rather than summary figures. The 0% implied probability suggests traders expect the actual reading to fall outside the specified range, though the precise range boundaries are not stated in the available market description.

Tokyo's August temperatures follow a consistent pattern shaped by the East Asian summer monsoon and urban heat island effects. Historical data from Haneda shows August highs typically cluster between 32–35°C, with extreme readings above 37°C occurring roughly once per decade. The 2010 heatwave pushed Tokyo to 40.8°C, whilst more recent Augusts (2019–2023) have seen peaks in the 34–36°C band. This historical distribution suggests the consensus has priced in either an unusually narrow range or a misalignment between the market's range and actual seasonal expectations.

Traders monitoring this market should track Japan Meteorological Agency forecasts released in early August 2026, which typically offer 10–14 day outlooks with reasonable accuracy for temperature extremes. Pacific typhoon activity during mid-August could suppress temperatures, whilst high-pressure systems from the Tibetan plateau tend to elevate them. The resolution methodology—prioritising Daily Observations over Day High & Low summaries—introduces a technical dependency on Wunderground's data collection practices at Haneda, which occasionally shows minor discrepancies with JMA official records. Any significant weather pattern shift or data reporting anomaly could shift the outcome materially from historical norms.

Methodology

This page reviews Highest temperature in Tokyo on August 20? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Who Will Win, which mirrors the Polymarket order book at 0% fees.

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.

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 Who Will Win. 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%.