Highest temperature in Hong Kong on May 31?

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Market context

Hong Kong's highest temperature on 31 May 2026 will be recorded by the Hong Kong Observatory and published in their Daily Extract dataset. The settlement window closes at midday UTC on that date, though final data publication may extend beyond the market deadline. Resolution hinges on the Observatory's official "Absolute Daily Max" figure in degrees Celsius to one decimal place.

May in Hong Kong typically sits at the threshold between spring and early summer, with mean daily maxima around 29–31°C depending on the specific week. Historical records show considerable year-to-year variation; the Observatory's climate data reveals May extremes ranging from approximately 33°C to 37°C over recent decades. The 0% crowd probability suggests traders are either awaiting clearer temperature forecasts or treating this as a placeholder market pending meteorological guidance. Cross-platform comparison shows no meaningful divergence between prediction markets and sportsbook operators, as weather derivatives remain a niche segment outside major betting platforms.

The key catalyst is the emergence of reliable extended-range forecasts in late April and early May 2026. Traders should monitor the Hong Kong Observatory's seasonal outlooks and any tropical cyclone activity in the western Pacific, which can suppress temperatures through cloud cover and rainfall. The El Niño/La Niña status and broader regional pressure patterns will influence whether May 31 falls within typical seasonal bounds or experiences anomalous heat. Until such forecasts materialise, the market's flat probability distribution reflects genuine uncertainty rather than consensus conviction.

Methodology

This page reviews Highest temperature in Hong Kong on May 31? across five venues. We show live odds for Polymarket-based markets (sourced from the Polygon order book); for other venues we list platform attributes, since the comparable contracts are not exposed via a public API on every venue. Every CTA points at Best Prediction Markets UK — the application we operate, where you trade directly against the Polymarket order book at 0% fees.

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 Best Prediction Markets 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.

What does it cost to trade on Best Prediction Markets UK?

Zero. Best Prediction Markets UK 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.

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.