Highest temperature in Shanghai on July 23?

Platform comparison

Market context

Shanghai’s highest temperature on 23 July will be taken from the Shanghai Pudong International Airport Station on Wunderground, so the market is about the *single-day peak reading* rather than the citywide average. That makes the relevant question whether the airport observation hits the next bracket up or down, not whether Shanghai feels broadly hot; July is typically one of the city’s hottest months, with average highs often cited around 32°C and broader July ranges extending into the mid-30s. [2][3]

The crowd’s 0% YES on the current setup should be read with caution on Polymarket, because this contract has 11 temperature bands and the live price distribution already shows the money concentrated in the 35°C and 36°C buckets rather than at the extremes. Polymarket quotes the market in implied probabilities, while Kalshi and Smarkets more often present decimal-style pricing and different fee treatment, so the same view can look materially different once commissions and spreads are included; Betfair adds a further layer because exchange liquidity and commission can move the effective price away from the headline odds. [1]

The main catalysts are the weather forecast revisions for eastern China, especially any change in the strength or timing of the Pacific subtropical ridge, cloud cover, and monsoon rain bands over the Shanghai area in the run-up to the 23 July observation window. Traders will also watch for airport-specific effects such as sea-breeze moderation and rainfall timing, because the resolution uses the station maximum on the day rather than a forecast high; the practical edge comes from comparing the station’s likely peak hour against the market’s narrow clustering around the mid-30s. [1][2][3]

Sources: 1 · 2 · 3

Methodology

We read Highest temperature in Shanghai on July 23? 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

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.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.