Lowest temperature in Hong Kong on July 31?

Platform comparison

Market context

Hong Kong’s **lowest temperature** for 31 July is usually decided by overnight or early-morning conditions at the Observatory, but the market only settles on the HKO’s final **“Absolute Daily Min (deg. C)”** once the Daily Extract is published. July in Hong Kong is typically warm at night, with published climate summaries showing average lows around the high-20s Celsius, so a very low outcome needs an unusual rain-cooled or typhoon-influenced setup rather than a normal summer day.[1][2]

That is why the current **2% YES** looks like a long-shot reading rather than a call on an ordinary July pattern: the historical reference point most traders have is how often Hong Kong’s minimums are pulled down by heavy rain or tropical systems. In 2019, for example, rain from Wipha drove the Observatory’s temperature down to **24.5°C**, the month’s lowest, on 31 July.[3] For platform comparison, Polymarket typically shows **implied probability** directly, while Kalshi, Betfair and Smarkets are easier to read in **decimal-odds** terms and may differ on fees and access; Betfair and Smarkets also depend more on local account eligibility and KYC than a venue that is open more broadly.

For catalysts, traders should watch whether the HKO posts the final daily extract and whether the day’s weather was affected by showers, thunderstorm warnings or a tropical cyclone track near southern China, because those are the main ways a July minimum can break lower than the seasonal norm. The observatory’s hourly readings already show how quickly Hong Kong temperatures can sit near the upper-20s overnight in late July, so any late rain band or stronger-than-expected cloud cover can matter to the final minimum, but the market cannot settle until the HKO finalises the day’s data.[7][11]

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 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.

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.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

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.