Edition 2026-09-25 The Ledger Archive API RSS Weather Trader
Milepost
1208

TheForecast Post

A chronicle of American weather and climate  ·  Friday, 25 September 2026

Boston, Massachusetts Revisions MILEPOST 1208

Boston's forecast for Saturday has moved 9°F warmer

59°F in the 20260922T12:00Z run, 69°F in the 20260925T00:00Z — the 3rd-largest revision of the 7 cities on the roster that moved at all. The current run's 10th-to-90th percentile spread at that hour is 13°F.

Successive cycles do not merely refresh a forecast; they leave a trail. For Saturday, October 3 at 00Z in Boston, that trail runs from 59.3°F in the 20260922T12:00Z cycle to 68.6°F in the 20260925T00:00Z — a move of +9.4°F across 8 runs.

The change is about half the run's 10th-to-90th percentile spread, so the earlier forecast is still inside the current range of outcomes.

Model NBM-QMD, via api.weather.city /v1/history. Percentiles are the same run's own.

The numbers in this piece, with what they are measured against
forecast revision for Saturday at 00Z
api.weather.city /v1/history (nbm-qmd)
9.4 °F normal 0.0 °F · 3 of 7
8 synoptic cycles
10th-to-90th percentile spread at that hour
api.weather.city (nbm-qmd)
12.6 °F normal 9.4 °F
current run
Milepost
1208 · laid 2026-09-25T10:25:14Z
Model
nbm-qmd · cycle 20260925T00:00Z
Desk
revision v1
Method
the same valid time read from successive synoptic cycles; the move is last run minus first run
Source
https://api.weather.city/v1/history
Digest
e23c829034e7ab4bc9c5e1ab5c6c2857bafda7e68f6f77b21bb5a89d6eb4ae46
Machine
JSON