Platform comparison
| Platform | YES odds | NO odds | Fee | KYC | Settlement | |
|---|---|---|---|---|---|---|
Polymarket (via BTC Prediction) Pick polygram.ink (preferred broker) |
61% | 39% | 0% (USDC on-chain) | No-KYC up to $1,500 | USDC, auto via UMA oracle | Open live market → |
Polymarket (direct) polymarket.com |
61% | 39% | 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 |
|---|---|
| 32°C | 61% |
| 33°C | 32% |
| 34°C | 8% |
| 31°C | 2% |
| 35°C | 2% |
| 27°C or below | 0% |
| 28°C | 0% |
| 29°C | 0% |
| 30°C | 0% |
| 36°C | 0% |
| 37°C or higher | 0% |
Market context
On 15 August 2026, the highest temperature recorded at Shenzhen Bao'an International Airport Station will determine the settlement outcome. The market will reference the Daily Observations table on Weather Underground rather than summary figures, establishing a precise measurement standard. Settlement occurs in USDC against the specific temperature range that captures the daily high.
Shenzhen's August climate is consistently hot and humid, with historical highs typically ranging between 32–35°C. Over the past decade, mid-August temperatures at Bao'an have rarely exceeded 36°C, though extreme heat events pushing toward 37–38°C occur roughly once every three to four years during particularly intense summer patterns. The 0% crowd probability suggests traders are pricing in either a cooler-than-normal August or confidence in sub-32°C outcomes, which would represent a significant departure from seasonal norms and warrant scrutiny of long-range forecasting models.
Key variables include the strength of the western Pacific subtropical high-pressure system and any tropical cyclone activity in the South China Sea during mid-August 2026. The China Meteorological Administration typically issues extended forecasts by late July; traders should monitor those releases alongside sea-surface temperature anomalies reported by NOAA. Any tropical system tracking toward the region would suppress temperatures through cloud cover and precipitation, whilst a dominant high-pressure ridge would amplify heat. Historical precedent suggests the 34–35°C range captures the modal outcome, making extreme tails less probable but not negligible given climate variability.
Methodology
This page reads Highest temperature in Shenzhen on August 15? 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 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.
- Can I use Bitcoin directly?
- No, Polymarket operates exclusively in USDC on Polygon. You can bridge BTC to USDC via an exchange or bridge service and deposit on Polygon — typically 10-30 minutes processing time.
- 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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