Highest temperature in Madrid on July 21?

Platform comparison

Market context

Madrid's peak temperature on 21 July 2026 will be measured at the airport weather station and resolved against historical temperature bands. The 0% implied probability suggests the market may not yet reflect typical summer heat patterns for the date, or traders are pricing in uncertainty around which temperature bracket will ultimately contain the day's high.

July in Madrid routinely produces temperatures exceeding 35°C, with the city's airport station recording highs in the 36–40°C range during peak summer weeks. Historical data from Wunderground shows 21 July has seen temperatures between 33°C and 38°C in recent years, placing it squarely within Madrid's hot season rather than its extreme tail. The current zero probability implies either very tight clustering around a single temperature band or minimal trading activity, which often masks value in weather markets where historical frequency distributions are well-established.

Traders should monitor European weather forecasting updates through early July 2026, particularly from AEMET (Spain's national meteorological agency) and major forecast models tracking Atlantic pressure systems. Heat domes affecting southern Europe typically develop two to three weeks before peak impact, making late June forecasts critical for positioning. The settlement window closes at midday on the day itself, meaning morning forecasts will be the final catalyst for any significant probability shifts before resolution against recorded airport data.

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 Who Will Win. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 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.