Highest temperature in Tokyo on August 18?

Platform comparison

Market context

Tokyo Haneda Airport will record a daily maximum temperature on 18 August 2026, with settlement determined by the highest reading in Weather Underground's Daily Observations table rather than the summary high-low figures. The market resolves to a temperature band containing that peak measurement in degrees Celsius. Current crowd pricing sits at 0% YES, suggesting either extreme confidence in a specific outcome or minimal trading activity establishing a floor.

August temperatures at Haneda typically range between 28–35°C, with the station's historical August averages clustering around 31–32°C. The 2% crowd probability reflects either a narrow band definition or sparse liquidity; comparable weather markets on crypto platforms show similar flatness when settlement windows extend beyond two years, as traders discount long-dated weather contracts heavily. Tokyo's summer heat has been volatile—the Japan Meteorological Agency recorded 37.5°C in central Tokyo on 20 August 2023—but Haneda's coastal location and airport microclimatic effects generally moderate extremes by 1–3°C versus inland readings.

Traders should monitor Japan's seasonal forecasts from late July 2026 onwards, particularly any Pacific typhoon activity or upper-atmosphere pressure patterns that could suppress or elevate August highs. The JMA issues monthly outlooks in early August that often shift market expectations materially. USDC settlement mechanics mean basis risk is minimal, though funding rates on longer-dated weather derivatives typically compress as the event approaches, creating arbitrage opportunities for early position holders if new information emerges.

Methodology

This page reads Highest temperature in Tokyo on August 18? on-chain. Polymarket's quote comes directly from the Polygon order book — the only comparable venue with on-chain settlement. Kalshi (USD, off-chain), Betfair (GBP/EUR, off-chain) and Manifold (play-money) are listed alongside for venue context. Every CTA routes to BTC Prediction, which mirrors the Polymarket order book directly.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

UK Frequently Asked Questions

Can I use Bitcoin directly?

No, Polymarket operates exclusively in USDC on Polygon. You can bridge BTC to USDC via an exchange or bridge service and deposit on Polygon — typically 10-30 minutes processing time.

How does UMA secure the resolution?

The UMA Optimistic Oracle uses a bond system: a proposer posts a bond, a two-hour challenge window opens. On dispute the losing side forfeits the bond — financial incentive for honest resolution.

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%.