Edition 2026-09-18 The Ledger Archive API RSS Weather Trader
Milepost
1125

TheForecast Post

A chronicle of American weather and climate  ·  Friday, 18 September 2026

The Ledger The Ledger MILEPOST 1125

The ledger, through September 18

Mean absolute temperature error runs 2.23°F at day 1 and 3.66°F at day 7, over 456,111 settled forecast-observation pairs.

Every forecast this network publishes for a station with an ASOS report is compared against that report once the valid time has passed, and the residual is written down. This is the standing table for August 19–September 18, 2026.

LeadNDFDNBMpairs
Day 12.282.2368,199
Day 22.482.4267,374
Day 32.722.6365,629
Day 42.962.8563,276
Day 53.243.1260,881
Day 63.533.4158,470
Day 73.823.6645,590
Day 83.9526,692

Mean absolute error, °F, temperature. ASOS reports at :53 and the forecast is stamped on the hour, so a forecast is paired with the nearest observation within 30 minutes and otherwise left unscored.

The numbers in this piece, with what they are measured against
day-1 mean absolute temperature error, NBM
Forecast Network verification ledger
2.23 °F of 34,761
August 19–September 18, 2026
day-3 mean absolute temperature error, NBM
Forecast Network verification ledger
2.63 °F of 32,642
August 19–September 18, 2026
day-5 mean absolute temperature error, NBM
Forecast Network verification ledger
3.12 °F of 30,320
August 19–September 18, 2026
day-7 mean absolute temperature error, NBM
Forecast Network verification ledger
3.66 °F of 27,907
August 19–September 18, 2026
day-1 mean absolute temperature error, NDFD
Forecast Network verification ledger
2.28 °F of 33,438
August 19–September 18, 2026
day-3 mean absolute temperature error, NDFD
Forecast Network verification ledger
2.72 °F of 32,987
August 19–September 18, 2026
day-5 mean absolute temperature error, NDFD
Forecast Network verification ledger
3.24 °F of 30,561
August 19–September 18, 2026
day-7 mean absolute temperature error, NDFD
Forecast Network verification ledger
3.82 °F of 17,683
August 19–September 18, 2026
Milepost
1125 · laid 2026-09-18T00:25:13Z
Desk
ledger v1
Method
ASOS reports at :53 and the forecast is stamped on the hour, so a forecast is paired with the nearest observation within 30 minutes and otherwise left unscored.
Source
/home/maue/forecastpoints/data/verify/2026-08.ndjson
/home/maue/forecastpoints/data/verify/2026-09.ndjson
Digest
48c474134371e983e28a9f03c3f30cd50a2be80b67b400e8082a5de93555a506
Machine
JSON