Highest temperature in Shenzhen on August 18?

Platform comparison

Market context

On 18 August 2026, the highest temperature recorded at Shenzhen Bao'an International Airport will determine this market's resolution. The contract currently trades at 0% implied probability across all temperature bands, suggesting either extreme uncertainty about which range will settle or a technical pricing anomaly. Polymarket's conditional token architecture on Polygon means traders holding USDC can enter positions across discrete temperature brackets, with settlement occurring against Weather Underground's Daily Observations table—the authoritative source rather than the Day High & Low summary that sometimes diverges from granular station data.

Shenzhen's August climate presents a narrow historical band for forecasting. The city experiences peak summer heat in mid-August, with daily highs typically ranging between 31–34°C, though extremes occasionally breach 35°C during heat waves. The 2023 August peak reached 34.2°C; 2022 saw 35.1°C on 16 August. These precedents suggest the market's zero probability across all ranges reflects either incomplete liquidity or a settlement specification issue rather than genuine forecasting consensus. Traders should verify which temperature brackets the market actually offers before committing capital.

The critical variable is tropical cyclone activity in the South China Sea during mid-August 2026. The Western Pacific typhoon season peaks in August, and any system approaching Guangdong province would suppress daytime highs through cloud cover and precipitation. China Meteorological Administration forecasts and tropical weather tracking from late July onwards will signal whether August 18 falls within a typical heat pattern or an anomalous cool spell. Current seasonal outlooks from international centres should be cross-referenced against historical frequency of such disruptions.

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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

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.

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%.