Highest temperature in Shenzhen on July 21?

Platform comparison

Market context

Shenzhen's July weather will determine where the highest temperature settles on 21 July 2026, measured at Bao'an International Airport Station. The current 0% implied probability on Polymarket suggests traders are pricing in either extreme confidence in a specific temperature band or minimal liquidity across the outcome range. Settlement hinges on Wunderground's historical data feed for that single day, with USDC collateral on Polygon backing whichever conditional token resolves to the recorded high.

Shenzhen's July temperatures historically cluster between 32–35°C, with occasional peaks above 36°C during heat waves. The city experiences its hottest period in July and August, driven by subtropical high-pressure systems and limited maritime cooling. Reviewing Wunderground's archive for previous July 21st readings provides the most direct comparable: in 2023, the high reached 33.8°C; in 2022, 34.4°C. These precedents anchor expectations, though year-to-year variation of 2–3°C is routine and outlier heat events pushing above 37°C occur roughly once per decade during peak summer months.

Traders should monitor seasonal forecasts from China's meteorological authority and Atlantic typhoon activity, which occasionally redirects moisture patterns into South China during mid-to-late July. El Niño or La Niña conditions influence regional heat intensity; current climate indices will crystallise by spring 2026. The settlement window closes at 12:00 UTC on 21 July, requiring traders to assess probability distributions well before the actual day arrives, since real-time weather forecasts only become reliable 7–10 days beforehand.

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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.

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.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.