Was the forecast right for Boston on Sat Aug 29?
Boston, Massachusetts · daily high temperature in °C · forecasts from each model's archived runs, verified against the BOS observations
9 days out, 4 models put Boston's Sat Aug 29 high anywhere from 24° to 28°; by the final call the field had settled to a median of 25°. The day verified at 23° against the BOS observations — partly cloudy.
GFS landed closest, off by 0.1°. ECMWF ran 3° hot.
What every model said, at every lead
Daily-high calls for Sat Aug 29 as each model's runs approached it — the last archived run per day. NBM and The Spread's own blend are consensus products and stay out of these ranges and rankings; the Boston scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 9d · 2026-08-20 | 24° | 25° | 26° | — | 28° | — | — | 24–28° |
| 8d · 2026-08-21 | 23° | 28° | 26° | 22° | 22° | — | — | 22–28° |
| 7d · 2026-08-22 | 23° | 23° | 27° | 24° | 26° | — | — | 23–27° |
| 6d · 2026-08-23 | 25° | 25° | 26° | 25° | 27° | 26° | — | 25–27° |
| 5d · 2026-08-24 | 23° | 26° | 25° | 23° | 23° | 24° | 25° | 23–26° |
| 4d · 2026-08-25 | 25° | 24° | 27° | 22° | 24° | 23° | 26° | 22–27° |
| 3d · 2026-08-26 | 24° | 25° | 25° | 23° | 21° | 23° | 27° | 21–27° |
| 2d · 2026-08-27 | 24° | 24° | 25° | 24° | 22° | 24° | 24° | 22–25° |
| 1d · 2026-08-28 | 24° | 25° | 25° | 25° | 21° | 24° | 25° | 21–25° |
| 0d · 2026-08-29 | 24° | 25° | 26° | 24° | 23° | 25° | 26° | 23–26° |
| actual | 23° |
Read it honestly
This is one date, not a league table. A model can win a day it deserved to lose; rankings only mean something over a window. For that, see which model has been most accurate in Boston — or every city The Spread scores.
Forecasts are what each model's archived runs said at the time, captured at The Spread's sweep times — never reconstructed after the fact. Truth is the BOS observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.