Highest temperature in Madrid on June 29?

Platform comparison

Market context

The real-world event at the heart of this market is the highest temperature recorded on 29 June 2026 at Adolfo Suárez Madrid-Barajas Airport, measured in degrees Celsius. In prediction markets, a YES share pays out if the temperature falls within the specific range the market targets, while a NO share pays out if it falls outside that range. Here, the crowd currently implies a 0% chance of the target range being hit, suggesting traders believe the day will be unusually cool or the target range is set far above likely conditions.

Historical data frames how to interpret this near-zero probability. Long-term averages show Madrid’s June daytime maximums typically reach 28°C, with low heat and humidity [1]. However, June 2026 has already seen extremes: the highest maximum recorded so far was 38.3°C on 22 June, and the all-time record for the month is 40.7°C from 28 June 2019 [9][10]. Notably, 30 June is statistically the warmest day of the month, averaging 31.8°C, meaning 29 June could still be mild by comparison [7]. The current 0% probability likely reflects expectations that temperatures will stay near the seasonal average rather than spike into the record-breaking range implied by the market.

Traders should monitor incoming weather forecasts and any official heatwave warnings from Spain’s meteorological agency, as these can shift expectations rapidly. A recent Washington Post report highlighted how a record heatwave in late June 2026 caused over 200 excess deaths across Spain, with temperatures exceeding 110°F (43°C) in some areas [6]. While that event occurred earlier in the month, its severity underscores the volatility of Madrid’s summer climate. Watch for updates from Wunderground, the official resolution source, and track whether forecast models predict a continuation of the heat or a return to the typical 28°C average [1]. No moral judgment on trading is needed; the facts show a high-stakes weather event with significant historical precedent for both extremes and moderation.

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

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 Prediction Market UK. 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 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.