Highest temperature in Madrid on July 3?

Platform comparison

Market context

Madrid is facing an intense summer heatwave from 2 to 5 July 2026, with daytime temperatures forecast to soar to 42°C or higher, far exceeding typical July highs for the city. This extreme event directly underpins the current market pricing, where the crowd-implied probability of the highest temperature falling within the lowest range sits at 0% YES, reflecting a near-universal belief that temperatures will breach that threshold.

Historical data frames this probability starkly: while 30 July is traditionally Madrid’s warmest day at 34.1°C, the 2026 heatwave is already the hottest since records began, with temperatures 1.6°C above normal across Spain’s first six months. Recent Reuters reporting confirms that temperatures reached 40°C on 21 June, and agencies warn that hundreds may have died from record heat, suggesting the 3 July peak could match or exceed the 45.4°C recorded on 18 July in Figueres.

Traders must monitor real-time updates from Wunderground for the Adolfo Suárez Madrid-Barajas Airport Station, as settlement depends on the highest temperature recorded at any time on 3 July. Key catalysts include official heatwave declarations from Spain’s meteorological agency and daily forecasts from AccuWeather, which currently project highs between 90°F and 103°F. The on-chain mechanics on Polymarket—using USDC on Polygon with conditional tokens—will resolve automatically once Wunderground publishes the verified data, making timely access to the source critical for position management.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Madrid on July 3? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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 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.

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 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 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.