Highest temperature in Shanghai on July 21?

Platform comparison

Market context

Shanghai faces its peak summer heat on 21 July 2026, with the market tracking the highest temperature recorded at Pudong International Airport. The current crowd-implied probability of 0% for the YES outcome suggests traders expect the temperature to fall outside the specific range offered, likely due to historical July peaks consistently exceeding 35°C. Historical data from recent years shows Shanghai’s July highs frequently reaching 37–39°C, making lower ranges statistically improbable and explaining the near-zero pricing on this platform.

Platform mechanics diverge sharply here: Polymarket displays implied probabilities like this 0%, whereas Kalshi, Betfair, and Smarkets use decimal odds, requiring traders to convert between formats. Fee structures also vary, with Polymarket often charging lower maker fees but higher gas costs on Ethereum, while Kalshi imposes flat trading fees and strict KYC requirements that limit global access. Smarkets and Betfair operate as betting exchanges with commission-based models, contrasting Polymarket’s no-commission, liquidity-driven approach.

Traders should monitor the daily Wunderground update for Pudong Airport, the official resolution source, and watch for any sudden thunderstorm forecasts that could suppress temperatures. Recent meteorological models from Meteoblue indicate scattered clouds and possible local thunderstorms for the afternoon, which may temporarily lower peak heat [2][3]. No official government announcements are expected, but real-time weather feeds will determine the final settlement value as the window closes at 12:00 UTC.

Sources: 1 · 2 · 3

Methodology

This page compares Highest temperature in Shanghai 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

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

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.

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.