Highest temperature in Chicago on July 27?

Platform comparison

Market context

Chicago's highest temperature on 27 July 2026 will be measured at O'Hare International Airport and resolved against historical records from Weather Underground. The market currently shows 0% probability across all temperature ranges, reflecting either a technical settlement issue or extreme illiquidity in the contract. Polymarket prices this as conditional tokens on Polygon, with USDC collateral backing each outcome bracket—traders would need to deposit stablecoin to establish positions across the available temperature bands.

July temperatures at Chicago O'Hare typically peak between 82°F and 88°F, with the station's all-time July record standing at 97°F (set in 1934). The past decade shows most late-July highs clustering in the mid-80s, though the summer of 2012 produced several days exceeding 90°F during a significant heat event. This historical distribution suggests the market's current zero-probability state is anomalous rather than reflective of genuine uncertainty about whether the airport will record *some* measurable high temperature on that date.

The National Weather Service Midwest office issues extended forecasts roughly ten days ahead of target dates; traders should monitor their Chicago office updates from mid-July onwards for seasonal pattern indicators. Lake Michigan's surface temperature and upper-atmosphere pressure systems in late July typically constrain Chicago's heat peaks below the extreme ranges seen in interior Midwest locations. Any significant heat dome tracking toward the Great Lakes region in the weeks preceding 27 July would represent the primary catalyst shifting probability mass toward higher temperature brackets.

Methodology

We track Highest temperature in Chicago on July 27? 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

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 PolyGram. 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.

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.