Highest temperature in Madrid on August 17?

Platform comparison

Market context

The market seeks the highest temperature recorded at Madrid-Barajas Airport on 17 August 2026, with resolution determined by Weather Underground's Daily Observations table rather than summary figures. The crowd currently assigns zero probability to any outcome, suggesting either incomplete market formation or an expectation that all temperature ranges fall below the minimum threshold offered.

Madrid's August temperatures have historically clustered in the 32–38°C range at the airport station, with extreme heat events pushing toward 40°C occurring roughly once per decade. The 2003 European heat wave saw Madrid reach 40.3°C in early August, whilst more recent Augusts have typically peaked between 34–37°C. A zero probability reading appears misaligned with seasonal norms; even conservative forecasts for mid-August in Madrid rarely suggest temperatures below 30°C, indicating potential mispricing in lower temperature brackets.

Traders should monitor European weather pattern developments from late July onwards, particularly the position of high-pressure systems over the Iberian Peninsula and any Atlantic moisture intrusions that might suppress peak temperatures. Spain's meteorological service (AEMET) typically issues seasonal outlooks by early August. The specific resolution source—Weather Underground's Daily Observations table at Barajas—matters considerably, as this airport station can record marginally different peaks than central Madrid due to urban heat island effects. Any significant deviation between preliminary forecasts and actual August conditions will likely shift market pricing substantially once trading becomes active.

Methodology

This page reviews Highest temperature in Madrid on August 17? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Who Will Win, which mirrors the Polymarket order book at 0% fees.

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.

UK Frequently Asked Questions

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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.