Highest temperature in Madrid on June 29?

Platform comparison

Market context

The underlying real-world event concerns the highest temperature recorded at Adolfo Suárez Madrid-Barajas Airport on 29 June 2026, a date historically prone to extreme heat. Current Polymarket pricing for this contract sits at 0% YES, implying the crowd believes the temperature will not exceed the specified threshold, despite Madrid’s June averages ranging from 95°F to 102°F (35°C to 39°C)[3]. This near-zero probability contrasts sharply with historical precedents, such as the 40.7°C peak recorded on 28 June 2019, just one day prior to the settlement date[9]. Furthermore, June 30 is climatologically the warmest day in Madrid, averaging 31.8°C, suggesting that late-June heatwaves are not anomalies but seasonal norms[6]. The 2026 heatwave, which reportedly caused over 200 excess deaths across Spain with temperatures exceeding 110°F (43°C) in some regions, further undermines the 0% market assumption[4].

Traders should monitor the latest Wunderground data for Barajas Airport, as the market resolves exclusively on this conditional token’s reported maximum for the day[2]. Key catalysts include the European Heat Health Watch system’s daily alerts and any sudden shifts in the Atlantic ridge, which typically drives scorching air into the Iberian Plateau. A recent Washington Post report highlighted that record heat in Spain this week has already triggered agency warnings, indicating that late-June 2026 could see similar extremes[4]. On-chain mechanics remain straightforward: positions are settled in USDC on the Polygon network, with conditional tokens determining payout based on the Wunderground temperature range[2]. Given the historical volatility and the ongoing 2026 heat crisis, the 0% probability appears detached from empirical reality, making this a high-risk, high-reward on-chain bet for those tracking real-time weather dependencies.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Madrid on June 29? 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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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 PolyGram. 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.

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.

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.