Highest temperature in Beijing on July 21?

Platform comparison

Market context

Beijing's peak daily temperature on 21 July 2026 will be recorded at the Capital International Airport meteorological station and resolved against historical data from Weather Underground. July represents the height of Beijing's summer monsoon season, when afternoon highs routinely exceed 35°C. The settlement mechanism relies on a single authoritative source—the airport station's daily maximum—making this market straightforward to verify but sensitive to measurement timing and station-specific microclimates.

Historical July temperatures at Beijing Capital Airport show a 30-year mean high of approximately 32–33°C, with extremes ranging from 29°C in cooler years to 41°C during heat waves. The 0% crowd probability suggests either market participants expect a specific temperature range to resolve, or the market interface requires explicit selection before probability displays. For programmatic traders, the key is establishing baseline expectations: typical July 21 highs cluster between 31–36°C, with outliers driven by Tibetan high-pressure systems or tropical moisture intrusions. Comparing this year's seasonal patterns against the 2023 and 2024 records provides calibration points.

Traders monitoring this market should track China's meteorological forecasts released 7–10 days prior to settlement, particularly from the China Meteorological Administration's extended outlook. Late-July Beijing weather depends heavily on the position of the subtropical jet stream and whether monsoon troughs penetrate northern China. Real-time feeds from Weather Underground update hourly, allowing conditional orders to trigger if forecasts shift materially. The airport station's elevation and urban heat island effects mean its readings typically run 1–2°C higher than surrounding rural areas, a systematic bias worth accounting for when comparing to broader regional forecasts.

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 Kalshi Fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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 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.