Highest temperature in Madrid on July 21?

Platform comparison

Market context

On 21 July 2026, Madrid's highest temperature will be measured at Adolfo Suárez Madrid-Barajas Airport Station and recorded by Wunderground. The market currently prices at 0% YES, reflecting either extreme confidence in a specific temperature range or insufficient liquidity across the available brackets. Settlement occurs at 12:00 UTC on that date, with resolution tied to the single highest reading captured during the full calendar day at the airport's official weather station.

Madrid's July temperatures follow a consistent pattern shaped by continental climate dynamics. Historical data from the airport station shows July highs typically range between 32°C and 36°C, with extreme readings occasionally exceeding 38°C during heatwave conditions. The 2022 European heatwave saw Madrid reach 40.5°C in early July, whilst more moderate years see peaks in the 33–35°C band. The 0% probability across all brackets suggests market participants either expect an outcome outside the predefined ranges or face fragmented liquidity that hasn't yet consolidated trader conviction into any single temperature band.

Traders monitoring this contract should track European weather forecasting models from mid-July onwards, particularly ECMWF and GFS outputs that typically show reliable signal 10–14 days ahead. Spain's national meteorological agency (AEMET) publishes weekly forecasts and heat alerts that often precede significant temperature swings. Any declared heat alert status for the Madrid region in the week prior would signal elevated probability for higher temperature brackets. On-chain mechanics remain straightforward: USDC deposits on Polygon settle conditional tokens to the winning bracket once Wunderground data confirms the day's maximum.

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Kalshi UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.