Highest temperature in Madrid on June 28?

Platform comparison

Market context

The underlying real-world event is the highest temperature recorded at Madrid-Barajas Airport on 28 June 2026, measured in degrees Celsius. Historical data shows that Madrid’s June averages hover around 28°C, with daytime highs typically reaching that level under low humidity[1]. However, extreme cases exist: on 28 June 2019, the airport recorded 40.7°C, the highest for that date in the 1920–2026 record[5]. This year’s June has already seen Spain break multiple heat records, including 43.7°C in Cantabria and 45.1°C in Andujar, suggesting a hotter-than-average pattern[3][7].

For a Polymarket trader, the current 0% YES probability implies the market expects temperatures far below the 40°C threshold needed to trigger a payout. Yet, the catalyst to watch is the ongoing heatwave and any official announcements from Spain’s meteorological agency (AEMET) regarding forecasted spikes for late June. Recent reports confirm Madrid experienced its warmest night on record, with temperatures not dropping below 26.2°C, indicating sustained heat pressure[4]. Traders should monitor AEMET’s daily bulletins and Wunderground’s live data for the airport station, as conditional tokens on Polygon settle based on these verified USDC-priced outcomes. The on-chain mechanics mean that even a single 40°C reading could flip the market, despite current pricing.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Madrid on June 28? 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

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.

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.