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 highs forecast to soar to 42°C or more, far exceeding typical July averages for the city[3]. This extreme event frames the current market pricing, where the 37°C outcome trades at 61% probability, while the 36°C outcome sits at 19%, suggesting traders are betting on a peak near the upper end of the stable high-pressure range[1]. Historical context reinforces this view: Spain’s first six months of 2026 were the hottest ever recorded, with temperatures 1.6°C above normal, and the country already experienced its first official heatwave in June, reaching 40°C[5][6].

Traders should monitor real-time updates from Wunderground for the Adolfo Suárez Madrid-Barajas Airport Station, as settlement depends exclusively on the highest temperature recorded at this location on 3 July 2026[1]. Key catalysts include AEMET’s daily forecasts, which recently indicated a daytime high of approximately 35°C for 2 July under stable high-pressure conditions, and any shifts in wind patterns or cloud cover that could alter peak temperatures[2]. The market resolves on-chain using USDC on the Polygon network, with conditional tokens determining payouts based on the final temperature range[1]. Given the heatwave alert and the potential for temperatures beyond 42°C, the 0% probability assigned to lower ranges reflects the crowd’s confidence in an extreme peak[1].

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.

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 Polymarket Legit?. 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 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.