Will the maximum temperature be >83° on Sep 30, 2026?

Market-implied high 78.2° vs Fair from NBM — ±—°. NBM supplies only the point forecast. Sonde derives the ±—° pricing uncertainty from time to the expected peak and disagreement among available models, then widens it because one public model is only one estimate. This uncertainty creates the probability and fair value for each bucket; it is not published by NBM.

Forecast board — predicted bucket

Each model has a point daily maximum forecast. The page maps that value into the venue bucket using the same half-degree settlement rounding the market uses. Settlement uses the NWS Daily Climatological Report for KPHL, not any model.

Microstructure

Resolution timing

Typical 90% lock-in in ~14.0h (by 5:00 PM) — the high can still move.

Timing from the last 92 days of station-coordinate weather analysis — real history, not the official climate report. Hourly sampling blurs the exact minute.