Highest temperature in Beijing on July 7?

Platform comparison

Market context

Beijing will experience its peak summer heat on 7 July 2026, with the highest temperature recorded at the Capital International Airport Station determining the outcome of this prediction contract. The current crowd-implied probability of 0% for a temperature above 32°C stands in stark contrast to historical patterns and analyst consensus, which frequently place July highs between 30°C and 36°C[3]. This divergence suggests a significant mispricing, as sportsbook lines and prediction-market odds on similar contracts, such as the 3 July event, show strong volume favouring 33°C to 34°C ranges rather than the lower extremes implied here[2].

Historical data frames this probability as an outlier; Beijing’s all-time high of 41.9°C occurred in July 1999, and the hottest day in 2010 reached 42.1°C, while average July highs rarely fall below 34°C (88°F)[1][4][5]. Recent records confirm this trend, with 2023 seeing temperatures reach 40°C and 2024 marking China’s hottest month in recent history[6][7]. Traders should monitor the Beijing Meteorological Bureau’s daily forecasts and any sudden shifts in regional humidity or cloud cover, as these are the primary catalysts for temperature deviations[3]. Authorities have already urged residents to limit outdoor time due to current heatwaves, indicating that the atmospheric conditions are primed for high temperatures rather than the cool spell implied by the 0% probability[1].

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

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 Best Prediction Markets 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 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.