Highest temperature in Beijing on July 31?

Platform comparison

Market context

Beijing’s highest temperature on 31 July is typically a summer heat question, with July in the city usually running around 31–32°C on the daily high and occasional spikes well above that. Historical weather summaries for Beijing show July as the hottest month, with average highs around 31°C and recorded extremes reaching 41.6°C in the 2016–2025 period, so a 0% crowd-implied probability on a July heat threshold is more a function of the market’s exact range mapping than of any belief that the day will be cool.[2][4][7]

For comparison, platforms read the same event differently. Polymarket-style markets usually show a direct implied probability, while Kalshi and Betfair often present decimal prices that need converting into probability, and Betfair’s commission can make the effective break-even price slightly worse than the headline quote. Smarkets also quotes in decimal terms and typically charges a commission on net winnings rather than embedding a wider spread, so the same Beijing temperature outcome can look very different after fees even when the underlying expectation is identical. For a resolution source tied to Beijing Capital International Airport Station on Wunderground, that matters because traders are effectively pricing a single-station reading rather than a citywide average.[20]

The main catalysts are the afternoon heat trend in Beijing, cloud cover, rainfall, and any late-day thunderstorms, which can cap the airport’s maximum even when the broader city feels hot. July in Beijing is also the rainy season, so short-lived convection can matter more than the monthly average. On a same-day market settling at 12:00 UTC, traders should watch the midday local forecast updates and airport observations rather than just the seasonal climatology, since the final high can still be set after the book is already active.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in Beijing on July 31? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live mid is the canonical probability; the side-by-side columns benchmark fees, KYC, settlement currency and deposit rails so you can choose the venue that fits your jurisdiction and trade size.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.