Highest temperature in Chicago on July 27?

Platform comparison

Market context

Chicago's peak temperature on 27 July 2026 will be recorded at O'Hare International Airport and resolved against historical weather data from Wunderground. The settlement window closes at midday UTC, meaning traders must account for the full diurnal cycle occurring in Central Time before the market locks. This timing creates a practical constraint: the highest temperature typically occurs in mid-to-late afternoon local time, so the resolution data will capture the complete daily range.

July temperatures at O'Hare cluster reliably between 78–88°F for daily highs, with extreme outliers rare. The 30-year average high for late July sits around 82°F; readings above 90°F occur in roughly 15–20% of years during this period, whilst sustained heat waves pushing past 95°F are infrequent. Traders evaluating the current 0% probability on any given temperature band should cross-reference historical distributions from the National Weather Service's Chicago office to calibrate which ranges carry genuine tail risk versus consensus expectations.

Programmatic traders should monitor the National Weather Service Chicago forecast updates in the week preceding 27 July, particularly any heat advisories or excessive heat warnings issued 3–5 days prior. Upper-air pattern shifts—specifically ridging over the Great Lakes region—drive the most significant temperature departures. Real-time API feeds from Wunderground can be queried post-settlement to verify the official O'Hare reading, though historical data typically stabilises within 24 hours of the observation date. Conditional order logic should account for forecast uncertainty narrowing as the date approaches, with material probability shifts likely only if anomalous upper-level patterns emerge in medium-range models.

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 Polymarket Review 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 Polymarket Review 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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Review UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.