Highest temperature in Madrid on August 9?

Platform comparison

Market context

Polymarket is pricing the Madrid airport high for 9 August at **37°C** with **100%** implied probability, and the contract settles in **USDC on Polygon** through conditional tokens once the Weather Underground daily observations for Adolfo Suárez Madrid-Barajas Airport are finalised. That means the tradable question is not the citywide headline forecast, but the exact highest Celsius reading logged in the station’s *Daily Observations* table up to the settlement cut-off, with the on-chain outcome redeeming only if the correct temperature band matches the recorded value.[1]

The market is reading against a hot late-summer Madrid pattern rather than an unusual spike. Forecasts around the date pointed to daytime highs in the **mid-to-high 30s Celsius** and persistent sunshine, with AccuWeather issuing a **moderate high-temperature warning** and a maximum near **38°C** for the wider area.[5][7][9] Historical climate context also supports why the contract is centred near the top of the distribution: Madrid’s August averages are typically around the low 30s Celsius for daily highs, while record August heat can reach the low-40s, including **42.7°C** at the airport station in the city’s broader records.[12][17]

For traders, the main catalyst is not a scheduled event but the evolution of the daytime heat profile and whether the airport station peaks above the forecast range before the settlement window closes. Any late strengthening of the heat advisory, cloud cover changes, or a surprise shower cooling the afternoon would matter most because Polymarket shares settle to the exact band, not an approximate city forecast.[3][9][10] The critical dependency is the final Weather Underground observation table, so the only useful check is whether the airport’s recorded maximum lands in the same bucket as the current 100% favourite.[1]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi UK, which mirrors the Polymarket order book directly.

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%.