Highest temperature in Shenzhen on July 20?

Platform comparison

Market context

Shenzhen is currently experiencing a humid summer day with scattered clouds and thunderstorm rain, where the maximum temperature has reached just 29°C at Bao'an International Airport [1]. This immediate weather reality aligns with the market’s current crowd-implied probability of 0% for any outcome suggesting extreme heat, as the atmosphere remains too unsettled for record-breaking highs. The settlement window closes at noon tomorrow, meaning the final resolution depends entirely on the peak reading recorded between now and that deadline, with current conditions already ruling out temperatures significantly above 30°C.

Historical data for mid-July in Shenzhen typically sees highs between 32°C and 35°C, yet the current 29°C maximum represents a notable deviation from the seasonal average [1]. In comparable years, persistent thunderstorm activity has frequently suppressed daytime temperatures, preventing the city from reaching its usual summer peaks. This pattern suggests the 0% probability is not an anomaly but a rational reflection of the active weather system currently dominating the region, which has already capped the day’s heat well below the thresholds required for most resolution ranges.

Traders should monitor the persistence of the thunderstorm rain and cloud cover through the night, as these are the primary catalysts preventing a temperature spike before the 12:00 UTC settlement [1]. No new weather announcements or schedule changes are expected to alter this trajectory, as the meteorological dependency rests solely on the natural dissipation of the current storm system. If the clouds break and rain ceases before dawn, a rapid temperature rise could occur, but the current forecast indicates continued scattered clouds and broken cloud layers that will likely maintain the ceiling near today’s observed maximum.

Sources: 1

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.