Highest temperature in Hong Kong on August 4?

Platform comparison

Market context

Polymarket is pricing the contract as a USDC-denominated claim on **Hong Kong’s hottest reading on 4 August**, with traders buying and selling conditional tokens on Polygon around a resolution source that will be the Hong Kong Observatory’s final “Absolute Daily Max (deg. C)” for the date. The crowd-implied price is still **0% YES**, so the market is effectively saying that none of the listed temperature bands has yet attracted meaningful conviction, even though the contract cannot settle until the Observatory publishes the finalized daily extract.

That near-zero pricing sits against a climate that is normally warm, humid, and rain-prone in August. Long-run guides and forecast summaries for Hong Kong point to daytime highs around **31°C to 32°C**, with frequent showers and high humidity, which means the relevant question for traders is less whether it will be hot than where the day’s peak lands once cloud, rain, or sunshine briefly break through. Polymarket’s own market page has recently framed the most likely outcomes as the **high-20s to around 30°C**, which is consistent with the city’s summer climatology rather than an outlier heat event.[7][8][16]

For a hands-on Polymarket user, the key catalysts are the Hong Kong Observatory’s short-range forecasts, any thunderstorm or typhoon-related advisories, and the final daily extract when it is posted. Forecast sources for 4 August have pointed to rain or showers with temperatures around **30°C to 31°C**, while the Observatory’s seasonal material underlines that August sits in peak summer and typhoon season, so small changes in cloud cover and rainfall can move the day’s maximum by a degree or two.[2][6][13][15][16]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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 does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.