Platform comparison
| Platform | YES odds | NO odds | Fee | KYC | Settlement | |
|---|---|---|---|---|---|---|
Polymarket (via BTC Prediction) Pick polygram.ink (preferred broker) |
95% | 5% | 0% (USDC on-chain) | No-KYC up to $1,500 | USDC, auto via UMA oracle | Open live market → |
Polymarket (direct) polymarket.com |
95% | 5% | 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 |
|---|---|
| 36°C | 95% |
| 37°C | 7% |
| 29°C or below | 0% |
| 30°C | 0% |
| 31°C | 0% |
| 32°C | 0% |
| 33°C | 0% |
| 34°C | 0% |
| 35°C | 0% |
| 38°C | 0% |
| 39°C or higher | 0% |
Market context
Shenzhen’s daytime heat is the core driver here, but the contract settles on the **highest observed temperature** at Shenzhen Bao’an International Airport, so the relevant number is the intraday peak rather than the headline high/low summary. Before midday UTC, the live forecast points to a very hot day: AccuWeather and Time and Date both show a forecast high of **97°F (about 36°C)**, while Weather Underground’s recent airport history already showed **98°F / 85°F** on 8 August, underlining that mid-30s Celsius readings are plausible in this pattern.[10][11][6]
The current **0% YES** crowd price looks disconnected from the weather setup and is more consistent with an initially inactive market than with a settled view on the temperature range. Comparable August climate data for Shenzhen puts typical highs around **31–33°C**, but the airport station can run hotter on clear, humid days, and the last 24 hours included a **99°F** reading on 9 August in the local history feed.[3][2] For a range-based market, the decisive issue is whether the airport’s daily maximum lands in the **36°C** band or nudges into **37°C**, which is exactly where the forecast cluster is concentrated.[8][15]
Traders should watch the daytime progression at the airport station, not just model guidance, because late-morning heating and any convective cloud build can shift the daily extreme materially. Weather Underground’s history page for ZGSZ is the stated resolution source, and the settlement window ends at **12:00 UTC**, so the final observation set will depend on the airport’s local conditions through the midday heat peak.[6] In crypto terms, the market is USDC-settled and mechanically simple, so if broader risk sentiment is in play, moves in BTC and ETH tend to matter only indirectly through positioning rather than through any fundamental link to Shenzhen weather.
Methodology
Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — sit alongside as off-chain reference points so you can see how the contract translates across regulatory and settlement regimes.
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.
- What does a transaction cost on Polygon?
- Polygon gas is typically under $0.01 per transaction. A full trade cycle (Approve + Order + Fill) totals around $0.03 — compared to $5-50 on Ethereum mainnet.
- 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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