Highest temperature in Tokyo on August 17?

Platform comparison

Market context

Tokyo's peak temperature on 17 August 2026 remains unforecast, with the settlement window now less than two years away. The 0% crowd probability reflects the inherent uncertainty in pinpointing a specific daily maximum more than 18 months in advance—a timeframe where meteorological models lose meaningful skill. August typically brings Tokyo's hottest conditions of the year, with daily highs routinely exceeding 33°C, though the precise range on any given date depends on factors (typhoon proximity, upper-level pressure patterns, urban heat dynamics) that cannot be reliably predicted at this distance.

Historical August records for Tokyo Haneda show considerable day-to-day variability within the month. Between 2010 and 2023, 17 August highs ranged from 29.8°C to 35.9°C, with no dominant pattern suggesting a particular outcome is more likely than others. This spread underscores why long-range temperature forecasts carry minimal predictive value; seasonal climatology alone cannot narrow the resolution range sufficiently to justify meaningful probability shifts this far out.

Traders should monitor updates to Japan Meteorological Agency seasonal outlooks, typically released quarterly, which may signal whether summer 2026 is expected to trend warmer or cooler than the 30-year normal. Wunderground's historical data quality for Tokyo Haneda is well-established, reducing settlement ambiguity. The market's reliance on the Daily Observations table rather than summary figures is a material distinction that resolvers should verify against the platform's actual data structure when the settlement date approaches.

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

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.

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%.