Highest temperature in Shenzhen on July 21?

Platform comparison

Market context

Shenzhen will experience its peak daily heat on 21 July 2026 at the Bao’an International Airport station, with the market now pricing a 31°C outcome at 98% probability. This near-certainty contrasts sharply with the 0% implied probability for any alternative range, suggesting the crowd views higher temperatures as virtually impossible for this specific date and location.

Historically, late July in Shenzhen typically sees highs between 30°C and 34°C, but the airport station often records slightly lower peaks than urban districts due to its coastal exposure. Comparable cases from 2023 and 2024 show 31°C as a frequent ceiling for this period, aligning with the current frontrunner. On platforms like Kalshi or Betfair, such a tight probability distribution would likely appear as decimal odds of 1.02 rather than a 98% implied probability, while fee structures and KYC requirements differ significantly: Polymarket offers crypto-native access with minimal identity checks, whereas Kalshi mandates US residency and full KYC, and Betfair/Smarkets operate under stricter European licensing.

Traders should monitor the daily Wunderground history for the Bao’an station, as resolution depends exclusively on this source. No major weather announcements are scheduled, but regional humidity and cloud cover patterns in the Pearl River Delta could act as subtle catalysts. A sudden shift in monsoon activity, though unlikely in mid-July, would be the only credible threat to the 31°C consensus. Recent climate data from the China Meteorological Administration confirms stable summer conditions for Guangdong, reinforcing the market’s confidence [1].

Sources: 1

Methodology

This page compares Highest temperature in Shenzhen 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

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.

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.