Highest temperature in Shenzhen on August 21?

Platform comparison

Market context

On 21 August 2026, the highest temperature recorded at Shenzhen Bao'an International Airport will fall into one of several defined ranges, measured in degrees Celsius and sourced from Weather Underground's Daily Observations table rather than summary figures. The market currently prices all temperature brackets at 0% probability on Polygon, reflecting either incomplete liquidity provision or early-stage contract formation before substantive trading activity. Settlement depends on precise data extraction from a specific weather station's granular observation records, not rounded daily summaries, which introduces a technical resolution dependency that traders should verify against historical Weather Underground methodology.

Shenzhen's August climate presents a narrow historical band for forecasting purposes. The city experiences peak summer conditions with average highs between 32–34°C, though extreme heat events occasionally push readings above 36°C. Between 2015 and 2024, August 21 specifically recorded highs ranging from 31°C to 35°C across most years, with only isolated instances exceeding 35°C during particularly intense heat waves. This ten-year window suggests the most probable outcome clusters in the 32–35°C range, though tropical storm activity or unusual atmospheric patterns could shift outcomes materially.

Traders should monitor China's meteorological forecasts released in late August 2026, particularly any typhoon or monsoon alerts affecting southern Guangdong province. The China Meteorological Administration typically issues extended forecasts 10–14 days ahead, which would become actionable by mid-August. Sea surface temperatures in the South China Sea and upper-atmosphere pressure patterns will determine whether August 21 experiences typical summer heat or anomalous cooling from weather systems. Historical precedent suggests extreme outliers (above 37°C or below 30°C) remain statistically unlikely for this specific date.

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

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 Polymarket Alternative UK. 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%.