Highest temperature in Istanbul on May 25?

Platform comparison

Active sub-markets

Market context

On 25 May 2026, the highest temperature recorded at Istanbul Airport (Atatürk/Yeşilköy) will fall into one of several defined ranges, measured in degrees Celsius by NOAA's automated weather station. The settlement hinges on a single data point: the peak temperature reading from that calendar day, with resolution occurring after all hourly observations are finalised. This is a straightforward meteorological fact-check rather than a predictive exercise, since the event occurs within the settlement window itself.

Istanbul's late-May climate typically produces highs between 26–28°C, though readings occasionally exceed 30°C during early heat waves. Historical May 25th maxima at the airport cluster around 25–27°C, with outlier years reaching 31–32°C during anomalous warm spells. The current 0% crowd probability suggests either insufficient liquidity, late-market positioning, or traders awaiting seasonal forecasts closer to the date. Across major platforms, Polymarket's decimal-odds format and Kalshi's binary structure handle temperature ranges differently; Betfair and Smarkets typically offer tighter spreads on weather once meteorological models converge within two weeks of the event.

Traders should monitor European weather models (ECMWF, DWF) from early May onwards, as jet-stream positioning and any Mediterranean heat domes will sharpen probability estimates. Turkish meteorological data from May 2025 will provide the most recent comparable baseline. KYC requirements vary significantly between platforms—Polymarket operates with lighter restrictions in certain jurisdictions, whilst Kalshi enforces stricter US-based verification. Fee structures on these niche weather markets differ materially; Smarkets' commission model favours smaller stakes, whereas Betfair's exchange format rewards larger matched volumes.

Methodology

This page compares Highest temperature in Istanbul on May 25? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. Live odds come from the Polymarket order book; the other venues' contract details are maintained manually because their APIs aren't directly comparable. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Where can I trade this market with the lowest fees?

On PolyGram, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

PolyGram is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, PolyGram triggers a quick verification flow that finishes in 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.