Highest temperature in Chengdu on July 20?

Platform comparison

Market context

Chengdu Shuangliu International Airport is expected to record its peak daily temperature on 20 July 2026, with historical data indicating July is the hottest month in Sichuan. Average daytime highs reach 30–35°C, while extreme records have climbed to 39°C during prolonged heat waves, with roughly 12 days annually exceeding 35°C[2][3]. The current crowd-implied probability of 0% for any outcome suggests a market error or mispricing, as Polymarket’s frontrunner outcome is 38°C at 100% probability, directly contradicting the zero-per-cent implied probability noted elsewhere[1].

Traders should monitor the China Meteorological Administration’s daily heatwave bulletins and Wunderground’s real-time station data for ZUUU, the official resolution source[1]. Recent forecasts confirm Sichuan is in its rainy season but remains very hot, with humidity amplifying perceived temperatures[2]. On platform comparison, Polymarket displays outcomes as implied probabilities (e.g. 100% for 38°C), whereas Kalshi and Betfair typically quote decimal odds, creating friction for cross-book arbitrage. Fee structures also diverge: Polymarket charges no trading fees but may impose withdrawal costs, while Smarkets applies a flat 2% commission on winnings, and Kalshi enforces KYC requirements that limit access for non-US traders.

The settlement window closes at 12:00 UTC on 20 July 2026, meaning any temperature recorded before that time at ZUUU determines the outcome. Given the 39°C historical extreme and consistent 35°C+ days, a 0% probability for all outcomes is statistically implausible unless the market has not yet opened liquidity or contains a technical glitch[2][4].

Sources: 1 · 2 · 3 · 4

Methodology

We read Highest temperature in Chengdu on July 20? 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.

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. Polymarket Alternative 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.