The ledger, through September 30
Mean absolute temperature error runs 2.23°F at day 1 and 3.88°F at day 7, over 514,950 settled forecast-observation pairs.
The LedgerWednesday, September 30, 2026The Ledger
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Milepost 1247
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 31–September 30, 2026.
| Lead | NDFD | NBM | pairs |
|---|---|---|---|
| Day 1 | 2.29 | 2.23 | 70,277 |
| Day 2 | 2.52 | 2.44 | 70,289 |
| Day 3 | 2.78 | 2.66 | 70,203 |
| Day 4 | 3.02 | 2.91 | 70,273 |
| Day 5 | 3.34 | 3.21 | 70,356 |
| Day 6 | 3.68 | 3.56 | 70,888 |
| Day 7 | 4.04 | 3.88 | 57,396 |
| Day 8 | — | 4.18 | 35,268 |
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 34,835 August 31–September 30, 2026 |
| day-3 mean absolute temperature error, NBM Forecast Network verification ledger |
2.66 °F | of 34,759 August 31–September 30, 2026 |
| day-5 mean absolute temperature error, NBM Forecast Network verification ledger |
3.21 °F | of 34,912 August 31–September 30, 2026 |
| day-7 mean absolute temperature error, NBM Forecast Network verification ledger |
3.88 °F | of 35,369 August 31–September 30, 2026 |
| day-1 mean absolute temperature error, NDFD Forecast Network verification ledger |
2.29 °F | of 35,442 August 31–September 30, 2026 |
| day-3 mean absolute temperature error, NDFD Forecast Network verification ledger |
2.78 °F | of 35,444 August 31–September 30, 2026 |
| day-5 mean absolute temperature error, NDFD Forecast Network verification ledger |
3.34 °F | of 35,444 August 31–September 30, 2026 |
| day-7 mean absolute temperature error, NDFD Forecast Network verification ledger |
4.04 °F | of 22,027 August 31–September 30, 2026 |
- Milepost
- 1247 · laid 2026-09-30T00:25:14Z
- 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.
- Stores
- /home/maue/forecastpoints/data/verify/2026-08.ndjson
/home/maue/forecastpoints/data/verify/2026-09.ndjson - Tagged
- I-500 Daily Weather · by rule, at build
- Digest
- dde3f2cef27ccf1483b0446231a76b9e05e7c85125adf9de75e11484974ee804