Platform comparison
| Platform | YES odds | NO odds | Fee | KYC | Settlement | |
|---|---|---|---|---|---|---|
Polymarket (via BTC Prediction) Pick polygram.ink (preferred broker) |
37% | 63% | 0% (USDC on-chain) | No-KYC up to $1,500 | USDC, auto via UMA oracle | Open live market → |
Polymarket (direct) polymarket.com |
37% | 63% | 0% | Geo-blocked in US/UK/EU | USDC, on-chain | Open live market → |
Kalshi kalshi.com |
— | — | Up to 7% per trade | US-only, KYC required | USD | Open live market → |
Betfair Exchange betfair.com |
— | — | 2-5% commission | Full KYC from first trade | GBP / EUR | Open live market → |
Manifold Markets manifold.markets |
— | — | Play-money (mana) | None — play-money | Mana (no cash-out) | Open live market → |
Outcome probabilities
Current market-implied probability for each outcome, from the live order book.
| Outcome | Probability |
|---|---|
| 34°C | 37% |
| 35°C | 27% |
| 33°C | 20% |
| 31°C | 11% |
| 36°C | 8% |
| 32°C | 7% |
| 37°C or higher | 1% |
| 27°C or below | 0% |
| 28°C | 0% |
| 29°C | 0% |
| 30°C | 0% |
Market context
On 19 August 2026, the highest temperature recorded at Shenzhen Bao'an International Airport Station will determine settlement of this market. The resolution mechanism specifies the Daily Observations table on Weather Underground as the authoritative source, with the Day High & Low summary section serving only as secondary reference in case of discrepancy. This distinction matters operationally: intraday peak readings in the observations log occasionally diverge from the rounded daily high figures displayed in summary views, particularly during rapid temperature swings or sensor calibration events.
Shenzhen's August climate presents a narrow band of outcomes. Historical data from the airport station shows August highs clustering between 32–34°C, with extreme readings rarely exceeding 35°C or falling below 31°C. The 0% crowd probability suggests traders are pricing either exceptional confidence in a specific temperature bracket or genuine uncertainty about which range the market's resolution categories actually span. August represents the tail end of Shenzhen's summer monsoon season; tropical systems tracking towards southern China in late August can suppress temperatures, whilst high-pressure systems locked over the region drive readings upward. The National Meteorological Centre's 10-day forecasts, typically issued around 10 August, will be the first concrete signal of atmospheric conditions shaping that week.
Traders should monitor tropical cyclone activity across the Western Pacific from mid-August onwards, as any system threatening the Pearl River Delta would materially shift temperature expectations downward. Conversely, sustained ridging of the Tibetan high-pressure system would favour elevated readings. Settlement occurs at 12:00 UTC on 19 August, allowing time for the full calendar day's observations to be recorded and published on Weather Underground before resolution.
Methodology
This page reads Highest temperature in Shenzhen on August 19? on-chain. Polymarket's quote comes directly from the Polygon order book — the only comparable venue with on-chain settlement. Kalshi (USD, off-chain), Betfair (GBP/EUR, off-chain) and Manifold (play-money) are listed alongside for venue context. Every CTA routes to BTC Prediction, which mirrors the Polymarket order book directly.
Resolution & payout
Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.
Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.
UK Frequently Asked Questions
- What are crypto prediction markets?
- Crypto prediction markets are on-chain smart contracts where you buy YES or NO shares on a future crypto event (e.g. "BTC above $100k by year-end"). The market price between 0¢ and 100¢ is the implied probability.
- Why USDC and not ETH or USDT?
- USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.
- 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%.
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