Highest temperature in Tokyo on August 21?

Platform comparison

Market context

On 21 August 2026, the highest temperature recorded at Tokyo Haneda Airport Station will fall into one of several defined ranges. In prediction markets, traders buy YES or NO shares on specific outcomes. A YES share pays out if the event occurs; a NO share pays out if it doesn't. This market asks traders to predict which temperature band will contain that day's peak reading, measured in degrees Celsius and sourced from Weather Underground's Daily Observations table rather than summary figures.

Tokyo's August climate is consistently warm and humid, with historical highs typically ranging between 32–36°C during mid-to-late summer. The Japan Meteorological Agency's records show that 21 August has seen temperatures exceed 35°C in roughly half of the past two decades, though extreme heat events above 37°C remain less frequent. The current crowd probability of 0% for the YES outcome suggests traders are pricing in either a specific temperature threshold that historical data indicates is unlikely, or uncertainty about how the resolution criteria will be applied given the emphasis on Daily Observations data rather than conventional high-low summaries.

Traders monitoring this market should track the Japan Meteorological Agency's seasonal forecasts and any El Niño or La Niña patterns that influence Pacific weather systems in August 2026. Urban heat island effects around Haneda Airport, which sits in a densely developed area, consistently elevate readings above surrounding regions. The distinction between Daily Observations and Day High & Low summaries matters operationally—different measurement protocols or timing windows could shift outcomes, making careful attention to Weather Underground's methodology essential before settlement.

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Prediction Market UK, which mirrors the Polymarket order book directly.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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

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%.