Highest temperature in Tokyo on August 21?

Platform comparison

Market context

On 21 August 2026, Tokyo Haneda Airport Station will record a daily maximum temperature in Celsius. This market resolves to whichever temperature band contains the highest reading logged in Weather Underground's Daily Observations table—the granular station data, not the rounded summary figures. The settlement window closes at 12:00 UTC on that date, meaning traders must account for the full calendar day's observations across Japan Standard Time.

August in Tokyo typically peaks between 32–35°C, though heat waves can push readings above 37°C. The 0% crowd probability suggests the market may be calibrated to exclude extreme outliers or reflect genuine uncertainty about which specific temperature band will be hit. Historical August data from Haneda shows considerable year-to-year variance; the 2023 summer saw sustained temperatures above 35°C for extended periods, whilst cooler Augusts have remained in the 30–32°C range. Comparable weather prediction markets on similar dates have resolved across a wide distribution, indicating that even seasonal norms provide limited predictive power without real-time meteorological input closer to the event.

From a regulatory standpoint, this market operates under German GlüStV provisions if accessed from the EU, with US CFTC oversight applying to American traders depending on the platform's licensing structure. Most prediction market platforms permit no-KYC participation up to approximately $1,500 notional exposure per user, which typically covers single-outcome weather markets of this type. Traders should verify their jurisdiction's classification of weather derivatives and confirm whether their platform's settlement mechanism aligns with local derivatives regulation before committing capital.

Methodology

This overview of Highest temperature in Tokyo on August 21? reviews the four comparable platforms from a regulatory perspective: which is accessible in your jurisdiction, where KYC kicks in, how the platform is classified by your country of residence. Live probability is the Polymarket mid; comparison columns show regulatory status, KYC thresholds and settlement options for each platform.

Resolution & payout

On Polymarket, resolution runs on-chain via UMA Optimistic Oracle. USDC payout is instant and automatic, with no KYC. Tax treatment depends on your jurisdiction — in the US, gains are usually ordinary income; in the UK, often capital gains. Consult a tax professional for your situation.

UK Frequently Asked Questions

Do I need to KYC for Polymarket Legal UK?

Not for lifetime trading volume under $1,500. Above that threshold, a quick KYC flow kicks in — ID, selfie, approximately 5-10 minutes. The threshold matches FATF travel standards for unregulated crypto platforms.

Is Polymarket regulated by the UKGC?

No. Polymarket is not licensed by the UK Gambling Commission (UKGC). It is a decentralised prediction market operated under US regulation. UK traders can use it but do not benefit from UKGC dispute resolution or player protection requirements.

What are the HMRC tax rules on Polymarket profits for UK traders?

Polymarket profits are treated as cryptocurrency disposal events by HMRC. Each USDC settlement is a taxable event subject to Capital Gains Tax (CGT). For 2026/27, the CGT rate is 18% (basic rate) or 24% (higher rate). The annual CGT exemption is £3,000. Report via HMRC Self Assessment if your total crypto gains exceed £3,000 or proceeds exceed £50,000.

Does Polymarket KYC apply to UK users?

Yes. Polymarket requires KYC (Know Your Customer) verification for all users, including UK residents. You must provide a government-issued photo ID and a selfie. The process typically takes 5–10 minutes via their ID verification provider.

What is the legal difference between Polymarket and Betfair Exchange for UK traders?

Betfair Exchange is UKGC-licensed, meaning UK consumer protections apply and winnings are typically tax-free. Polymarket is not UKGC-licensed — it operates under decentralised blockchain rules. Profits from Polymarket are subject to HMRC CGT as crypto disposals. Choose based on your regulatory preference and tax situation.