Highest temperature in Tokyo on August 20?

Platform comparison

Market context

Tokyo's highest temperature on 20 August 2026 will be measured at Haneda Airport Station and recorded in Weather Underground's Daily Observations table, with settlement occurring at 12:00 UTC that day. The current Polymarket pricing reflects 0% probability across all temperature bands, suggesting either minimal liquidity or a technical issue with contract initialisation on Polygon. USDC holders pricing this contract are effectively treating all outcomes as equally unlikely at present, which creates an arbitrage opportunity once conditional token liquidity improves and the market discovers its true price discovery mechanism.

Historical August temperatures at Tokyo Haneda show a consistent pattern: the past five years have recorded daily highs between 32–36°C during mid-August, with 2023 reaching 35.2°C and 2022 peaking at 34.8°C. The Japan Meteorological Agency's seasonal forecasts for summer 2026 will be the primary catalyst traders should monitor, particularly any advisory updates issued in late July regarding heat waves or unusual atmospheric patterns. Recent summers have seen occasional spikes above 37°C during extreme heat events, though such occurrences remain statistically rare for this specific date and location.

Traders should verify the exact settlement methodology before committing capital, as the market explicitly prioritises Weather Underground's Daily Observations table over its Day High & Low summary—a distinction that has historically created discrepancies of 0.1–0.3°C in some cases. The contract's reliance on a single weather station means localised microclimatic conditions at Haneda will determine outcomes rather than broader Tokyo metropolitan readings.

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 Polymarket Scam?, which mirrors the Polymarket order book at 0% fees.

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 Scam?. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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%.