Highest temperature in Hong Kong on May 22?

Platform comparison

Active sub-markets

Market context

Hong Kong’s highest temperature on 22 May is already priced at 0% for the YES side on Polymarket, where traders lock USDC into conditional tokens on Polygon before the market settles against the Hong Kong Observatory’s final “Absolute Daily Max” reading. With the settlement window ending at 12:00 UTC, the contract is effectively a midday snapshot of the city’s maximum temperature, not a full-day weather bet in the abstract.

May in Hong Kong is usually warm to hot, with the Hong Kong Observatory’s climatology and private forecasts pointing to daytime highs around 29–30°C, though individual May extremes have been higher. The Observatory’s own records show May monthly mean maximums have reached 32.5°C, with other late-May readings above 31°C in past years. That history matters because a 31°C print is not unusual in the broader seasonal context, but it still depends on a very warm morning and early afternoon rather than the more typical mid-to-high 20s profile.

For traders, the key catalysts are the Observatory’s intraday updates, any late-morning heating under clear skies, and whether showers or cloud cover suppress the peak before the 12:00 UTC cutoff. AccuWeather’s May outlook for Hong Kong has suggested highs in the high 20s to low 30s Fahrenheit-converted band, consistent with a warm late-spring regime, but the market resolves only on the Observatory’s final extract. That means the on-chain price should be read against the timing of the official daily maximum, not the afternoon forecast after settlement has effectively closed.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on May 22? 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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

On PolyGram, 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.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does it cost to trade on PolyGram?

Zero. PolyGram routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.