Was the forecast right for Boston on Tue Aug 4?
Boston, Massachusetts · daily high temperature in °C · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
8 days out, 5 models put Boston's Tue Aug 4 high anywhere from 26° to 28°; by the final call the field had settled to a median of 30°. The day verified at 29° against the ECMWF IFS analysis — clear.
AIGFS landed closest, off by 0.0°. UKMO ran 2° hot.
What every model said, at every lead
Daily-high calls for Tue Aug 4 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 |
|---|---|---|---|---|---|---|---|---|
| 8d · 2026-07-27 | 26° | 28° | 27° | 27° | 26° | — | — | 26–28° |
| 7d · 2026-07-28 | 27° | 29° | 27° | 22° | 23° | — | — | 22–29° |
| 6d · 2026-07-29 | 27° | 29° | 27° | 28° | 29° | 24° | — | 24–29° |
| 5d · 2026-07-30 | 27° | 30° | 27° | 28° | 28° | 30° | 29° | 27–30° |
| 4d · 2026-07-31 | 28° | 29° | 25° | 22° | 25° | 26° | 28° | 22–29° |
| 3d · 2026-08-01 | 27° | 29° | 28° | 29° | 24° | 27° | 29° | 24–29° |
| 2d · 2026-08-02 | 28° | 29° | 29° | 26° | 29° | 30° | 31° | 26–31° |
| 1d · 2026-08-03 | 28° | 29° | 29° | 30° | 28° | 31° | 31° | 28–31° |
| 0d · 2026-08-04 | 28° | 29° | 30° | 30° | 29° | 31° | 31° | 28–31° |
| actual | 29° |
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 ECMWF IFS analysis (temperature_2m_max). Archive depth varies by city; receipts exist only for dates the archive watched arrive.