Highest temperature in Hong Kong on July 31?

Platform comparison

Market context

Hong Kong’s **highest temperature on 31 July** is the key event, and this market turns on the Hong Kong Observatory’s final “Absolute Daily Max” reading in Celsius rather than on any private forecast or city-wide average. Because the contract settles to a temperature band, the exact decimal value matters: the Observatory reports to one decimal place, so a close outcome can shift a trade between adjacent ranges even if the day feels broadly “hot”. The current **0% YES** crowd price is therefore best read as a statement about the chosen band, not about whether Hong Kong will be warm on the day.

Historically, late July in Hong Kong is one of the warmest periods of the year, and the Observatory’s July climate ranking shows monthly maximums in the mid-30s °C, with records reaching 35.7°C in 1968 and 35.6°C in 2016.[3] The Observatory also recorded 36.1°C on 27 July 2023, illustrating that extreme highs are possible in this part of the calendar.[7] That said, daily outcomes can be tightly pinned by showers, cloud cover and synoptic changes; the Observatory noted thunderstorms in the early hours of 31 July 2023 after a very hot spell.[7] For comparison, a recent Hong Kong update reported 31°C at the Observatory and 33°C in some outlying areas on a summer afternoon, underlining how localised heat can be.[9]

For platform comparison, Polymarket-style markets typically show a direct probability, while Kalshi, Betfair and Smarkets often express the same view through prices or decimal odds, with the trader then backing out implied probability. The practical difference on a one-day weather settlement is fees and access: exchanges like Betfair and Smarkets usually add commission on winnings, whereas regulated US venues such as Kalshi rely on account verification and jurisdictional eligibility, which can matter more than tiny pricing differences when the contract is range-based. The main catalysts are straightforward: watch the Observatory’s hourly readings on 31 July, then the later Daily Extract publication that finalises the official maximum.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest 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 Kalshi Alternative, 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.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Kalshi Alternative offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.