Highest temperature in Shanghai on August 20?

Platform comparison

Market context

Shanghai's weather on 20 August 2026 will depend entirely on the monsoon patterns and any tropical systems active in the Western Pacific during late summer. The 0% crowd probability suggests traders are either awaiting clearer atmospheric data or treating this as a placeholder market pending seasonal forecasts. Current conditions in early 2026 provide limited predictive value for a date nearly two years away, though historical August temperatures at Pudong International Airport typically range between 25–35°C, with extremes occasionally reaching 37–38°C during heat waves.

August represents Shanghai's hottest month climatologically, with the city sitting in the path of the East Asian summer monsoon. Historical records show that extreme heat events—temperatures exceeding 37°C—occur roughly once every two to three years during this period, often driven by high-pressure systems stalling over eastern China. The 2013 heat wave produced readings above 38°C; conversely, cooler Augusts with maxima around 28–30°C have followed years with stronger tropical cyclone activity or earlier monsoon withdrawal. These precedents frame the range of plausible outcomes for any given 20 August.

Traders should monitor tropical cyclone forecasts issued by the China Meteorological Administration and Japan Meteorological Agency from July onwards, as these directly influence August precipitation and cloud cover. Additionally, the timing of the East Asian summer monsoon's retreat—typically occurring in late August—will shape whether high-pressure dominance or moisture-laden systems prevail. Weather Underground's Daily Observations table at Pudong station remains the sole resolution source, making station-specific microclimatic factors relevant to final settlement.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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.

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%.