Highest temperature in Madrid on July 3?

Platform comparison

Market context

The real-world event driving this market is the peak daily temperature recorded at Adolfo Suárez Madrid-Barajas Airport on 3 July 2026, with settlement relying on Wunderground data. Current crowd-implied probability for a specific outcome sits at 0%, yet historical patterns and immediate forecasts suggest a high likelihood of extreme heat. In July, Madrid typically sees daily highs between 31°C and 36°C, rarely exceeding 37°C, though this year defies the norm. Recent Met Office and BBC Weather forecasts indicate stable high pressure and clear skies pushing temperatures near 36°C, while a concurrent heatwave alert warns of daytime peaks soaring to 42°C or higher across the region[1][3].

A power-user evaluating this market programmatically would script a bot to monitor Wunderground’s hourly updates and cross-reference with AccuWeather’s July 2026 forecast, which projects highs ranging from 90°F to 103°F (32°C to 39°C)[4]. The primary catalysts to watch are official heatwave declarations and real-time temperature spikes; Reuters reported Spain’s first official heatwave of 2026 on 21 June, with Madrid hitting 40°C, setting a precedent for sustained extreme conditions[5]. Traders should also track dependencies like high-pressure system stability and UV index warnings, as these directly influence peak temperatures. The 0% probability likely reflects a market mispricing or a specific range mismatch, given the documented trend of temperatures far exceeding typical July averages[3][5].

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

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 Kalshi Fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi Fees trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.