Highest temperature in Hong Kong on June 21?

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Market context

Polymarket is pricing this Hong Kong heat contract at **0% YES**, so the market is currently treating a qualifying maximum on 21 June as effectively ruled out and the **USDC-settled conditional tokens** as pointing to the opposite side. For a trader, the underlying event is simple: the Hong Kong Observatory’s final **“Absolute Daily Max (deg. C)”** for the day must fall inside the listed band, and the contract only resolves once that extract is published on Polygon-linked market infrastructure and finalised by the source.

Historically, Hong Kong can deliver very hot June readings, but the Observatory’s own climate pages show that the month’s highest *average* maximums are well above 31°C in recent records, while individual daily spikes can run hotter still.[2] Recent reporting also shows how quickly the city can reach extreme levels: the Observatory recorded **36.1°C** on a recent hottest day of the year, and another summer solstice reached **34°C** in a comparable heat event.[1][4] That matters because the market is not about whether June is warm, but whether *this specific date* prints into the settlement range.

The main catalysts are the Observatory’s daytime updates, any hot-weather or very hot weather warnings, and whether a subtropical ridge or persistent clear-sky conditions keeps maximum temperatures elevated into the afternoon. The key dependency is the Hong Kong Observatory’s final daily extract, since the market cannot resolve until the official figure is published; interim headlines or intraday readings only matter insofar as they signal where the final maximum may land.[7][3]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote (Polymarket), four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi UK, which mirrors the Polymarket order book directly.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

On Kalshi 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.

Is this market available outside the US?

Kalshi UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

What does it cost to trade on Kalshi UK?

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

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Kalshi 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.