Highest temperature in Hong Kong on May 31?

Platform comparison

Active sub-markets

Market context

On 31 May 2026, the Hong Kong Observatory will record the day's highest temperature in degrees Celsius. This market settles on that single data point, published in the Observatory's Daily Extract once the meteorological day closes and official records are finalised. The settlement window extends to midday UTC on that date, allowing time for the Observatory to publish verified readings.

Hong Kong's May temperatures typically range between 28–32°C, with historical daily maxima clustering around 30–31°C during late May. The 0% crowd probability reflects the market's current state rather than meteorological likelihood; such weather markets often show sparse early trading activity until nearer the event date. Comparable May temperature outcomes from recent years—including 2023's 31.8°C and 2022's 32.1°C on similar dates—provide calibration points for assessing which temperature bands carry genuine predictive value versus those reflecting thin liquidity.

From a regulatory standpoint, this market's accessibility depends on jurisdiction and account status. Under German GlüStV rules, prediction markets on weather events fall outside gaming licensing if they meet information-market criteria, though operators must verify compliance locally. US CFTC oversight applies to derivatives on weather indices, though binary prediction markets occupy a grey area pending clarification. For UK-based traders, the £1,500 no-KYC threshold on polymarket-kyc.co.uk means positions below that stake avoid full identity verification, though operators retain anti-money-laundering obligations. Traders should confirm their local regulatory position before committing capital, as weather derivatives classification varies by jurisdiction and position size.

Methodology

We track Highest temperature in Hong Kong on May 31? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

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.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket KYC UK, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket KYC UK triggers a quick verification flow that finishes in minutes.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.