Lowest temperature in Chicago on Sep 24, 2026?

📊 Market Summary

🌦️ Lowest temperature in Chicago on Sep 24, 2026?

6 options total

🎯 Best Trade

• Action: 60° or above — YES @ 95%

• Confidence: 🟡 MEDIUM · Uncertainty: LOW

• Why:

• The NWS point forecast high of 69°F and the observed 62.6°F reading point to a mild night, making a 58-59°F minimum a narrow miss rather than the base case.
• The dossier's own Polymarket comparison shows 58-59°F at 40% on a different date, but that market is $0-volume and internally contradictory, so it is not a reliable cross-check.
• With model spread at only 2.7°F and the station already warm, the probability mass sits above 60°F, leaving 58-59°F as a secondary outcome.

📈 Where the Market Stands

Verdicts compare my own read against the market price — 🟢 UNDERPRICED (market has it too low) · 🔴 OVERPRICED (market has it too high). The analysis below is the why.

🔬 9-Pillar Analysis (Meteorological Method)

🌡️ 1. Forecast Consensus

My Vegas Line reads the 60°+ bucket as the heavy favorite at 95%, and the NWS point forecast for Sep 24 (69°F high, partly sunny) plus the observed 62.6°F reading at Midway already logged today support a mild overnight low rather than a cold one.

📊 2. Ensemble Spread

Raw multi-model spread for Sep 24 is only 2.7°F (GFS 66.6, ECMWF 66.3, ICON 69), tight enough that a single 2°F band call is defensible, though the spread widens to 4.6-5°F by Sep 26-28.

⏳ 3. Forecast Skill Decay

This is a same-day/near-term resolution with the station already at 62.6°F, so skill decay is minimal — the forecast horizon is short and the observed floor is already known.

📈 4. Historical Base Rate

Late-September Chicago (Midway) climatological lows cluster in the mid-to-upper 50s, making a 60°+ minimum a warm-tail outcome rather than the norm, which is why the market's 95% on 60°+ is aggressive.

🔀 5. Model Divergence

If the outlier ICON run (69°F) is right the warm side wins comfortably; if the cooler ECMWF/GFS grid values (66.3-66.6°F) verify, the low still lands near or above 60°F, so no model kills the favorite.

📍 6. Micro-Climate Bias

Midway (KMDW) is an urban heat-island station that runs warmer than outlying Chicago sites, biasing the overnight minimum upward and reinforcing the 60°+ bucket.

🌀 7. Storm Track

No tropical or severe storm system is tracking toward Chicago — the NHC results cover Atlantic/Pacific systems and a New England nor'easter, none of which threaten a cold push into the Midwest.

💰 8. Market Pricing

LOW - the market is thin ($2,495 volume) with internally contradictory dossier quotes (47°F or below at 99% alongside 66°F or higher at 98%), so cross-platform signals are unreliable and the NWS station data is the only trustworthy anchor.

⚡ 9. Contrarian Check

The main contrarian risk is that the 95% on 60°+ is overpriced for a late-September night where climatology favors mid-50s lows; a clear, calm, dry night with radiational cooling could drop Midway into the 50s and kill the favorite.

⚠️ Disclaimer: AI can make mistakes. This is not financial advice, and not a meteorological forecast — verify against NWS/NOAA and current model output before placing any trades.