Highest temperature in Madrid on July 21?

Platform comparison

Market context

Madrid's peak temperature on 21 July 2026 will be recorded at Adolfo Suárez Madrid-Barajas Airport Station and resolved through historical weather data from Wunderground. The settlement window closes at midday UTC, meaning the highest reading across the entire calendar day—from 00:00 to 23:59 local time—determines the outcome, though traders should note the data refresh lag typical of weather archives.

Historical precedent suggests July temperatures in Madrid cluster heavily in the 35–40°C range. The city's 30-year average high for late July sits around 35.5°C, with extremes reaching 42–43°C during heat waves. The 0% crowd probability indicates either extreme confidence in a specific temperature band or insufficient liquidity across all ranges. Comparable markets on European summer temperatures typically see clustering around modal outcomes rather than even distribution, suggesting traders have identified a narrow expected range based on seasonal patterns and climate models available now.

Programmatic traders should integrate European weather forecasting APIs—particularly ECMWF or GFS model outputs—to track ensemble predictions as July 2026 approaches. The Wunderground data source requires direct scraping or API access to capture intraday highs; conditional orders tied to forecast thresholds from Spain's Agencia Estatal de Meteorología could automate position adjustments. Watch for heat dome formation patterns across southern Europe in early July, which typically drive Madrid temperatures upward by 5–8°C above seasonal norms. The airport station's location in a relatively open area means urban heat island effects are minimal compared to central Madrid readings.

Methodology

We track Highest temperature in Madrid on July 21? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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 Polymarket Bot UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Bot UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.