Highest temperature in Tokyo on August 19?

Platform comparison

Market context

Tokyo's daily maximum temperature on 19 August 2026 will be measured at Haneda Airport Station and recorded in Weather Underground's Daily Observations table. The market resolves to the temperature range containing that single highest reading, with explicit precedence given to the granular observation data over any summary high-low figures that may differ. This distinction matters for automated resolution: traders building conditional order logic or data-feed integrations need to query the correct WU endpoint to avoid settlement disputes.

August in Tokyo typically peaks between 32–35°C, though extreme heat events have pushed readings above 37°C in recent years. The 2023 summer saw Tokyo record 37.5°C on multiple days, whilst the 2010 heatwave reached 39.9°C at nearby stations. Historical volatility around this date is modest—most years cluster in the 33–36°C band—which contextualises why the crowd currently assigns zero probability to certain upper ranges. Traders evaluating this market should cross-reference Japan Meteorological Agency (JMA) seasonal forecasts and multi-model ensemble data from late July 2026 to calibrate tail-risk positioning.

Catalysts include the JMA's monthly outlook (typically issued mid-July), which flags heat anomalies or monsoon patterns affecting the Kanto region. El Niño or La Niña conditions in mid-2026 will shape atmospheric circulation; any tropical cyclone approach in mid-August could suppress temperatures or introduce measurement noise. Programmatic traders should monitor WU's data quality flags and cross-validate against JMA's official Haneda readings, as occasional sensor drift or maintenance windows can create discrepancies between sources before final settlement.

Methodology

We track Highest temperature in Tokyo on August 19? 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

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 Polymarket Review UK. 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%.