Highest temperature in Madrid on July 21?

Platform comparison

Market context

Madrid's highest temperature on 21 July 2026 will be measured at Adolfo Suárez Madrid-Barajas Airport Station and resolved against historical records via Wunderground. The settlement window closes at midday UTC on that date, capturing the full diurnal cycle through the morning hours. Current crowd-implied probability sits at 0%, suggesting traders are either awaiting resolution data or treating this as a calibration exercise against established temperature benchmarks for Madrid in mid-summer.

July temperatures in Madrid typically peak between 35–40°C, with historical records from the airport station showing consistent patterns across decades. The city's continental climate produces reliable summer heat, though specific daily maxima vary by 2–4°C depending on atmospheric conditions and urban heat dynamics. Comparable markets tracking European summer temperatures have shown that prediction-market participants generally anchor to long-term climate normals rather than year-to-year anomalies, particularly when settlement depends on official meteorological stations rather than modelled forecasts.

Traders monitoring this contract should track European weather pattern developments in early July 2026, particularly Atlantic pressure systems and North African heat advection that drive Madrid's summer extremes. The Spanish meteorological agency (AEMET) publishes seasonal outlooks and monthly forecasts that often precede prediction-market repricing. Any significant deviation from typical July conditions—such as an early heat dome or unseasonable Atlantic influence—would shift implied probabilities across temperature bands. The resolution mechanism's reliance on a single airport station eliminates urban microclimate variance, making this contract sensitive primarily to synoptic-scale weather drivers rather than localised effects.

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

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 Best Prediction Markets. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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.