Highest temperature in Chicago on June 30?

On Polymarket, traders set prices by buying and selling outcome shares in an automated market maker. On Polymarket, prices reflect that venue's order book, liquidity, and how traders price the outcome right now. Each outcome—such as the 92–93°F range—has a price between 0 and 100 cents, reflecting the implied probability that outcome will occur. Higher prices indicate stronger trader conviction; lower prices suggest skepticism. As new information arrives, traders adjust their positions, moving prices up or down. The spread between bid and ask prices tightens when volume is high and widens during quieter periods, directly reflecting market liquidity and confidence.

This market resolves around Jun 30, 2026, once the highest temperature recorded in Chicago for that day becomes verifiable from credible public sources. The outcome is determined by comparing the final official reading against the predefined temperature ranges offered in the market. Traders holding shares in the correct outcome receive their payout, while incorrect positions expire worthless. Resolution typically occurs within hours of market close, pending confirmation of the day's peak temperature from reliable meteorological data.

Major weather pattern shifts, updated seasonal forecasts, and real-time atmospheric data will drive price movements in this market. Tropical systems, heat domes, or unexpected cold fronts can dramatically alter expectations. As June 30 approaches, daily high-temperature forecasts from the National Weather Service and other agencies will narrow uncertainty and trigger trading surges. Historical climate anomalies, urban heat island effects, and even air quality events can influence final temperatures. Traders monitor long-range models, medium-range updates, and short-term nowcasts to adjust positions and capitalize on evolving weather intelligence.