Highest temperature in Beijing on June 28?

Platform comparison

Market context

The real-world event hinges on the highest temperature recorded at Beijing Capital International Airport on 28 June 2026, measured in degrees Celsius and resolved via Wunderground data. This single metric determines the market outcome, with the settlement window closing at 12:00 UTC on that day. The current crowd-implied probability of 0% for any outcome below 34°C suggests traders expect extreme heat, aligning with recent historical patterns where Beijing has shattered June records.

Historical cases frame this probability starkly: in June 2023, Beijing soared to 41.1°C, marking its hottest June day in over 60 years and smashing the previous record[1][3]. Average June highs typically range from 29°C to 32°C, rarely dipping below 23°C or exceeding 36°C[4], yet recent heatwaves have pushed temperatures well beyond these norms[8]. A power-user approaching this programmatically would note that the 0% probability for lower ranges reflects a statistical outlier expectation, not a baseline average, making conditional orders on higher thresholds a logical hedge.

Traders should monitor upcoming heatwave forecasts and cold air intrusion schedules, as these are the primary catalysts for temperature deviations. The fourth and strongest heatwave of the year, lasting from 21 to 30 June, previously drove Beijing’s temperature above 41°C[8], indicating that similar conditions could persist. A recent Reuters report confirms that heatwaves returning to northern China have already set new June records, suggesting that without significant cold air, temperatures will likely remain in the extreme range[1]. Programmatic strategies should weight these dependencies heavily when evaluating entry points.

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

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?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Bot UK. 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 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.