Highest temperature in Shanghai on August 3?

Platform comparison

Market context

Shanghai’s highest temperature on 3 August will be set by the daytime peak at Pudong airport, so the market is really a call on whether the city manages a hot, humid summer day rather than a single instant reading. The broad August climatology points to typical Shanghai highs around 32–33°C, with forecast services showing late-summer daytime ranges in the low 30s and, in some cases, much warmer spikes into the mid-30s Celsius.[1][8][12][16]

That backdrop helps explain why a 0% YES price can be misleadingly compressed on some books. On Polymarket, the quoted price is usually read as an implied probability; on Kalshi, it is likewise a probability-style market, while Betfair and Smarkets present decimal odds that must be converted into implied probability and adjusted for commission, which can make a low-probability contract look even less attractive after fees. For this specific event, the key comparison point is that different platforms may be pricing the same heat risk through different lenses: exchange-style odds on Betfair/Smarkets versus direct probability framing on Polymarket and Kalshi, with KYC access also varying by jurisdiction and venue.

The main catalysts are the latest forecast updates, whether afternoon convection or thunderstorms build, and how much cloud cover and humidity suppress or amplify the daily maximum. Recent guidance is not uniform: one source has Shanghai around 33°C with humid conditions on 3 August, while another shows a wider range of highs around 35°C and thunder risk, and current Shanghai observations are already in the low 30s with muggy air.[2][6][11][17] Traders should watch for any sharp revision in short-range forecasts, because this market resolves from the highest airport-station temperature on the day, not the city average or the morning reading.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in Shanghai on August 3? 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.

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.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Robinhood Prediction Markets has a different geo footprint and routes to Polymarket's order book at 0% fees.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Robinhood Prediction Markets offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.