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 sparse liquidity across all brackets.

Guangzhou's July climate is consistently hot and humid. Historical data from the same airport station shows July highs typically range between 32–35°C, with occasional peaks above 36°C during heat waves. The city experienced a 40.3°C reading in August 2023, though July tends slightly cooler. Comparing this market across platforms reveals structural differences: Polymarket displays decimal odds and charges 2% on both sides, whilst Kalshi uses implied probability notation with tiered fees starting at 0.5% and offers direct US-based settlement. Betfair's exchange model allows lay betting at varying odds, and Smarkets similarly fragments liquidity across multiple price points. For a weather market with binary-like resolution (a specific temperature band), Polymarket's flat fee structure may favour larger positions, whereas Kalshi's lower entry fees suit smaller retail traders testing weather prediction models.

Traders should monitor China Meteorological Administration forecasts released in early July 2026, which typically provide 10–14 day outlooks. El Niño or La Niña patterns influence East Asian summer temperatures; current oceanic conditions will shape whether July 2026 trends toward historical norms or anomalies. Airport station data occasionally records maintenance gaps, though Baiyun's automated systems are generally reliable.

Methodology

This page compares Highest temperature in Guangzhou on July 21? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Polymarket Alternative, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). On-chain settlement clears in minutes — the fastest payout path of the four.

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.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Polymarket 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. 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.