Highest temperature in Chicago on July 27?

Platform comparison

Market context

Chicago's peak temperature on 27 July 2026 will be measured at O'Hare International Airport and resolved against historical Weather Underground data. The 0% crowd-implied probability suggests traders are either extremely confident in a specific range or the market has attracted minimal liquidity. July temperatures at O'Hare typically peak between 82–88°F, with the airport's all-time July record standing at 97°F set in 1988. The median high for late July sits around 84°F, making extreme outliers—either unusually cool days below 75°F or heat-wave conditions exceeding 95°F—statistically uncommon but not unprecedented.

The 2026 forecast window remains too distant for reliable meteorological guidance; conventional weather models lose skill beyond 10–14 days. Traders should monitor mid-July 2026 atmospheric patterns and any developing heat domes or cool fronts affecting the Midwest, which typically become predictable 5–7 days beforehand. Historical analogs matter here: Chicago experienced a 97°F day in July 1988 and regularly sees 90°F+ temperatures during summer heat waves, though such extremes occur in roughly 20–30% of July days. The current zero probability likely reflects either a technical issue with market initialisation or extreme confidence in a narrow temperature band, creating potential arbitrage opportunities once the market develops meaningful depth and competing probability estimates emerge across other platforms.

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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.

Do I need to KYC for this market?

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