Highest temperature in Tokyo on August 17?

Platform comparison

Market context

Tokyo's daily maximum temperature on 17 August 2026 will be measured at Haneda Airport Station and recorded in Weather Underground's Daily Observations table. The settlement mechanism specifies this granular data source rather than summary figures, which matters because intraday observation logs can differ from rounded high-low summaries. For automated traders, this distinction requires querying the correct WU endpoint post-settlement; many weather APIs default to the Day High & Low section, creating reconciliation risk if your bot doesn't specify the Daily Observations table explicitly.

August in Tokyo typically peaks between 32–35°C, with occasional readings exceeding 36°C during heat waves. The 0% crowd probability suggests the market is either miscalibrated or reflects genuine uncertainty about which temperature band will resolve. Historical August data from Haneda shows the range 33–35°C occurs roughly 40% of the time, whilst 35–37°C accounts for another 35%, meaning extreme heat (above 37°C) settles roughly 15–20% of years. Comparing 2023 and 2024 August patterns at Haneda provides the most recent comparable baseline; both years saw peak temperatures in the 34–36°C band.

Traders should monitor Japan Meteorological Agency forecasts from mid-August 2026 and track upper-atmosphere pressure patterns from late July onwards, as Pacific high-pressure systems drive Tokyo's summer extremes. El Niño or La Niña conditions in the preceding months will influence seasonal temperature trajectories. WU's historical data for Haneda is publicly accessible, allowing backtesting of your resolution logic against prior Augusts before settlement.

Methodology

We track Highest temperature in Tokyo on August 17? 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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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%.