Highest temperature in Madrid on August 9?

Platform comparison

Market context

Madrid’s real-world trigger is the **highest recorded temperature at Adolfo Suárez Madrid-Barajas Airport on 9 August**, taken from Weather Underground’s **Daily Observations** table rather than the summary high/low line. For a programmatic workflow, that means scraping or polling the station history page, then mapping the maximum observed Celsius value into the market’s settlement bands; if the daily maximum is updated before the first datapoint for 10 August appears, revisions still count, which matters for bots that close exposure late. [11][1]

The current crowd price at 0% YES sits far below the weather guidance available in comparable forecasts. WMO’s Madrid forecast for 9 August shows **24°C to 36°C**, while AccuWeather and Timeanddate both point to a very hot day around **98°F/37°C**, with clear skies and low rain risk, and WeatherSpark’s August climatology shows Madrid often reaches the high 30s even if the long-run average is lower. That combination usually pushes a market into the upper bands unless a cooler morning, cloud cover, or wind shift clips the airport maximum. [5][2][3][8]

A trader watching this mechanically would focus on whether the airport station prints a peak above the market’s next threshold before midday UTC, because the settlement window ends at **12:00 UTC**. The key dependencies are the station’s local observation timing, any late-edited daily records on Weather Underground, and whether the highest value lands in the first published daily cycle or is revised afterwards; copy-trading or conditional orders can be tied to those checks rather than to generic city forecasts. The crowd’s 0% reading may therefore reflect stale pricing, a missing read-through to the source table, or a belief that the relevant maximum has effectively already been locked in. [1][11]

Sources: 1 · 2 · 3 · 4 · 5

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

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.

UK Frequently Asked Questions

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.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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%.