Highest temperature in Guangzhou on July 21?

Platform comparison

Market context

Guangzhou will record its highest daily temperature on 21 July 2026, measured at Baiyun International Airport Station. The settlement hinges on a single data point from Wunderground's historical records, making this a straightforward weather observation market with minimal interpretation risk. The 0% crowd probability suggests either extreme confidence in a specific temperature range or thin liquidity across competing outcomes.

Guangzhou's July climate is consistently hot and humid, with historical highs typically ranging between 33–37°C. The city experiences peak summer conditions during late July, though tropical systems occasionally moderate temperatures. Comparable markets on Kalshi and Polymarket for Asian weather events show divergent pricing patterns: Kalshi's decimal odds format and tighter spreads often reflect more efficient pricing on weather outcomes with clear historical baselines, whilst Polymarket's AMM-based pricing can lag on niche geographic markets. Betfair's weather book tends to offer deeper liquidity on major cities but charges commission on winnings, whereas Kalshi's flat fee structure favours high-probability outcomes. Smarkets similarly uses decimal odds but has narrower reach in Asian weather markets.

Traders should monitor seasonal weather forecasts released 10–14 days before the settlement date, particularly from the China Meteorological Administration and international models tracking monsoon activity. Any tropical cyclone formation in the South China Sea during early July could suppress temperatures significantly. The settlement window closes at 12:00 UTC on 21 July, requiring traders to account for timezone conversion when cross-referencing real-time airport data against Wunderground's historical records.

Methodology

We read Highest temperature in Guangzhou on July 21? 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

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.

Which platform is accessible globally?

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

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Kalshi 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.