Highest temperature in Tokyo on August 19?

Platform comparison

Market context

Tokyo's weather on 19 August 2026 will be shaped by the tail end of Japan's summer monsoon season, when the city typically experiences peak heat stress. The 0% crowd probability reflects uncertainty about which temperature band will be recorded at Haneda Airport Station rather than scepticism about heat itself—August in Tokyo routinely produces daily highs between 32–35°C. Recent shifts in global circulation patterns have made late-summer forecasting more volatile; the Japan Meteorological Agency's seasonal outlooks for 2026 remain provisional, with monsoon intensity and timing still subject to revision as we approach mid-year.

Historical August records at Haneda show considerable year-to-year variation. The station recorded 35.1°C on 19 August 2013 and 33.4°C on the same date in 2019, illustrating the range traders should expect. Extreme heat days (above 37°C) occur in Tokyo but remain statistically uncommon for any given date; they cluster around mid-to-late July rather than mid-August. The resolution mechanism's reliance on Weather Underground's Daily Observations table rather than summary figures introduces a technical dependency—discrepancies between reporting sources have occasionally shifted outcomes by 0.1–0.3°C, which could matter at range boundaries.

Traders should monitor the Japan Meteorological Agency's monthly forecasts (typically issued around the 20th of each preceding month) and any Pacific typhoon activity in early August, which can suppress temperatures through cloud cover and rainfall. El Niño or La Niña conditions developing through 2025–2026 will influence broader patterns, though their effect on a single date remains inherently difficult to predict.

Methodology

We track Highest temperature in Tokyo on August 19? 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 Prediction Today. 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%.