Lowest temperature in Hong Kong on July 31?

Platform comparison

Market context

Hong Kong’s low on 31 July will be set by the Hong Kong Observatory’s **Absolute Daily Min** reading for that date, and the market can only resolve once the Daily Extract is finalised. In practical terms, that means the outcome is tied to a single official decimal-Celsius figure, not to an intraday forecast or a rounded daily low, so prices should move only when the Observatory publishes the completed record.[1][3]

A 2% yes-implied probability points to an outcome that is materially below the city’s normal July pattern. The Observatory’s 1961–1990 normals put the mean minimum for 31 July at **26.2°C**, while recent July climatology and past weather summaries show Hong Kong usually spends late July with overnight lows in the high 20s and very warm, humid conditions.[2][3][6] That makes a sub-forecast-style cold reading unusual rather than impossible, especially if rain, cloud cover or a broader trough suppresses the night-time minimum; July 2023, for example, ended with showery thunderstorms in the small hours of 31 July before improving later in the day.[3]

For platform comparison, Polymarket-style pricing is usually read directly as an implied probability, whereas Betfair and Smarkets are better compared on decimal odds after commission, which can materially change the effective break-even on a market with a low quoted chance. KYC and access also differ: regulated exchange venues such as Betfair and Smarkets are generally more restrictive by jurisdiction, while cross-platform traders often find the same weather outcome can trade at different implied probabilities because of fee drag, liquidity depth and whether the market is exposed in probability or odds format.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Lowest temperature in Hong Kong on July 31? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Robinhood Prediction Markets, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Robinhood Prediction Markets has a different geo footprint and routes to Polymarket's order book at 0% fees.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.