Highest temperature in Tokyo on August 19?

Platform comparison

Market context

On 19 August 2026, Tokyo Haneda Airport Station will record a daily maximum temperature, with traders on Polymarket currently pricing the entire range at 0% YES across all temperature brackets. This suggests either extreme confidence in a specific outcome already priced into a different market structure, or minimal liquidity and participation in this particular contract. The settlement hinges on Weather Underground's Daily Observations table for Haneda—not the summary high-low figures—creating a technical distinction that occasionally produces discrepancies worth monitoring.

August represents Tokyo's hottest month climatologically, with daily highs typically ranging between 32–35°C, though heat waves can push readings toward 37–38°C. Historical precedent matters here: the Japan Meteorological Agency recorded 41.1°C in Kumagaya (Saitama Prefecture) in July 2018, whilst Tokyo itself peaked at 39.5°C in August 2013. Haneda's coastal location and airport infrastructure create a microclimate slightly cooler than central Tokyo, generally suppressing extremes by 1–2°C relative to inland stations. The 0% crowd probability suggests traders expect temperatures to fall outside whichever bracket this market covers, or that the contract's technical specifications—specifically the Daily Observations sourcing requirement—create sufficient uncertainty to deter participation.

Traders should monitor Japan Meteorological Agency forecasts from mid-August 2026 and track any Pacific typhoon activity, which can dramatically alter temperature trajectories. El Niño or La Niña conditions developing through summer 2026 will influence broader heat patterns across East Asia. The settlement window closes at 12:00 UTC on 19 August, requiring resolution within hours of the final observation, leaving minimal room for data corrections or disputes.

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

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

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.

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%.