Platform comparison
| Platform | YES odds | NO odds | Fee | KYC | Settlement | |
|---|---|---|---|---|---|---|
Polymarket (via Prediction Today) Pick polygram.ink (preferred broker) |
91% | 9% | 0% (USDC on-chain) | No-KYC up to $1,500 | USDC, auto via UMA oracle | Live odds → |
Polymarket (direct) polymarket.com |
91% | 9% | 0% | Geo-blocked in US/UK/EU | USDC, on-chain | Live odds → |
Kalshi kalshi.com |
— | — | Up to 7% per trade | US-only, KYC required | USD | Live odds → |
Betfair Exchange betfair.com |
— | — | 2-5% commission | Full KYC from first trade | GBP / EUR | Live odds → |
Manifold Markets manifold.markets |
— | — | Play-money (mana) | None — play-money | Mana (no cash-out) | Live odds → |
Outcome probabilities
Current market-implied probability for each outcome, from the live order book.
| Outcome | Probability |
|---|---|
| 32°C | 91% |
| 33°C | 6% |
| 34°C | 2% |
| 28°C or below | 0% |
| 29°C | 0% |
| 30°C | 0% |
| 31°C | 0% |
| 35°C | 0% |
| 36°C | 0% |
| 37°C | 0% |
| 38°C or higher | 0% |
Market context
Hong Kong's weather on 17 August 2026 will be shaped by the tail end of the summer monsoon season, when the territory typically experiences peak heat and humidity. August is consistently the warmest month in Hong Kong's meteorological calendar, with daily maxima regularly exceeding 32°C. The Hong Kong Observatory's historical records show that mid-August temperatures have ranged from 29.3°C to 36.3°C over the past three decades, with the modal outcome clustering around 33–34°C on typical days.
The 0% crowd probability reflects genuine uncertainty about which specific temperature band will be recorded, rather than doubt about whether a reading will occur. Historical volatility matters here: whilst August averages sit near 32.5°C, individual days can deviate significantly based on typhoon proximity, upper-atmosphere circulation patterns, and urban heat island effects across Hong Kong Island and Kowloon. The Observatory's daily maximum measurements, published in their climate extracts, represent the single highest temperature recorded during a 24-hour period at their official station.
Traders should monitor the Western Pacific typhoon season activity in early August, as tropical systems can either suppress temperatures through cloud cover or elevate them through pre-storm heating. The Observatory publishes preliminary daily data within 24 hours of observation, though final verification may take several additional days. Sea surface temperatures in the South China Sea and atmospheric pressure patterns across Southeast Asia in the week preceding 17 August will be the primary drivers of whether conditions favour the cooler or warmer end of the typical August range.
Methodology
We track Highest temperature in Hong Kong on August 17? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.
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
- 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.
- What does Polymarket cost to trade?
- Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.
- 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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