Platform comparison
| Platform | YES odds | NO odds | Fee | KYC | Settlement | |
|---|---|---|---|---|---|---|
Polymarket (via BTC Prediction) Pick polygram.ink (preferred broker) |
40% | 60% | 0% (USDC on-chain) | No-KYC up to $1,500 | USDC, auto via UMA oracle | Open live market → |
Polymarket (direct) polymarket.com |
40% | 60% | 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 |
|---|---|
| 27°C | 40% |
| 26°C | 34% |
| 28°C | 18% |
| 29°C | 9% |
| 25°C | 2% |
| 30°C | 1% |
| 32°C or higher | 1% |
| 22°C or below | 0% |
| 23°C | 0% |
| 24°C | 0% |
| 31°C | 0% |
Market context
Hong Kong’s highest temperature on 3 August will be set by the Hong Kong Observatory’s final “Absolute Daily Max” reading, published later in the daily extract rather than by intraday forecasts. At 1am UTC, the market is still awaiting the day’s official data, so the current 0% Yes probability mostly reflects the absence of a resolved reading rather than a settled weather outcome.
For context, Hong Kong August temperatures often sit in the high 20s to low 30s Celsius, but the city can still spike much higher during hot spells. Recent reporting shows the Observatory has already logged multiple heat-related peaks in 2026, including maxima of 34°C to 35.6°C and outlying districts above 36°C or even 38°C, which is the sort of pattern that keeps upper bands in play if cloud cover and rain do not dominate[3][6][9][11]. By contrast, the market’s current pricing around 27–28°C on Polymarket suggests traders are leaning towards a damp, cloudier day, with the contract now anchored more to the Observatory’s published maximum than to any headline forecast[2].
Traders should watch the Observatory’s regional weather updates, any late-morning or afternoon forecast revisions, and the timing of the daily extract publication, because the settlement source is the official one-decimal Celsius maximum, not a private model or airport reading[4][10]. On-chain, the contract still settles in USDC, so the key mechanics are the same as other crypto prediction markets: liquidity shifts in spot BTC and ETH can affect risk appetite broadly, but the immediate driver here is whether Hong Kong’s intraday conditions produce a reading above or below the crowded 27–28°C band[2].
Methodology
This page reads Highest temperature in Hong Kong on August 3? 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.
FAQ
- 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.
- How does UMA secure the resolution?
- The UMA Optimistic Oracle uses a bond system: a proposer posts a bond, a two-hour challenge window opens. On dispute the losing side forfeits the bond — financial incentive for honest resolution.
- How volatile are crypto prediction markets?
- Crypto markets react to spot prices — a 5% BTC move typically shifts a "BTC above X by date" market 10-20%. Polymarket crypto market liquidity is usually six-figure USD, sufficient for active trading.
- Which crypto markets exist on Polymarket?
- Currently active markets include BTC/ETH/SOL price targets, halving dates, ETF approvals, hard-fork outcomes and Layer-2 TVL thresholds. The list updates weekly; biggest volume sits on BTC and ETH price forecasts.
- Are crypto prediction markets taxable in the US?
- In the US, prediction market gains are typically treated as ordinary income or short-term capital gains depending on holding period. Consult a tax professional for your specific situation — we cannot provide tax advice.
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