Highest temperature in Istanbul on July 4?

Platform comparison

Market context

The underlying event is the NOAA-recorded peak temperature at Istanbul Airport on 4 July 2026, a single data point that will determine the settlement of this weather contract. Current crowd-implied probability sits at 0% for any outcome outside the 26°C range, yet ensemble forecasts from global models suggest a likely maximum near 25–27°C, driven by northerly flow [1]. This creates a stark divergence: while prediction markets assign 97% probability to 26°C, long-term climatological averages for early July in Istanbul historically run higher, typically between 27°C and 29°C [2]. Sportsbook lines on similar heat contracts often reflect this historical baseline, whereas prediction markets appear to have overcorrected for recent northerly anomalies, creating a notable mispricing against analyst consensus on regional warming trends.

Traders must monitor the real-time NOAA data stream for Istanbul Airport, specifically the "Temp" column updates as the settlement window closes at 12:00 UTC on 4 July [1]. The primary catalyst is the persistence of northerly flow, which has suppressed temperatures in recent ensemble runs, though recent extreme heat waves in Turkey, including a national record of 50.5°C in July 2025, suggest underlying volatility that could disrupt current models [7]. Analysts note that while daily highs rarely exceed 90°F (32°C) in Istanbul, the 2015–2017 heat waves caused significant mortality, indicating that extreme outliers remain possible despite current low implied probabilities [4]. The market’s 0% probability for alternatives ignores this historical volatility, leaving traders exposed if the northerly flow breaks before the final data point is published.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Best Prediction Markets UK, which mirrors the Polymarket order book directly.

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 Best Prediction Markets UK. 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'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.