Highest temperature in Madrid on August 17?

Platform comparison

Market context

Madrid's highest temperature on 17 August 2026 will be measured at Adolfo Suárez Madrid-Barajas Airport and recorded in Weather Underground's Daily Observations table. The settlement mechanism specifies this primary source explicitly to avoid discrepancies with summary forecasts, which matters for traders building automated resolution monitors. The current crowd probability of 0% suggests either extreme confidence in a specific temperature range or insufficient liquidity across all brackets.

August temperatures in Madrid historically cluster between 32–38°C, with extremes occasionally reaching 40°C during heat waves. The 17th falls within the peak summer period when thermal patterns are relatively stable compared to shoulder seasons. Reviewing Weather Underground's historical data for Madrid-Barajas across previous Augusts provides the baseline for calibrating range expectations; traders should cross-reference AEMET (Spain's national meteorological agency) historical records to validate the platform's reporting consistency. A 0% crowd probability on any single range suggests either that range is genuinely implausible given climatology, or the market has concentrated liquidity elsewhere.

Traders monitoring this market should set alerts for European heat dome forecasts issued by Météo-France and DWD (Germany's meteorological service) in early August 2026, as these often precede Spanish heat waves by 7–10 days. AEMET's own extended forecasts, typically published mid-month, will sharpen expectations closer to settlement. For programmatic approaches, establishing a data pipeline from Weather Underground's API to capture Daily Observations readings in real time eliminates reliance on manual checks, particularly useful given the 12:00 UTC settlement window may fall outside standard market-closing hours.

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 Fees. 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 Kalshi Fees 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.