Was the forecast right for Boston on Sat Aug 1?
Boston, Massachusetts · daily high temperature in °C · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
5 days out, 7 models put Boston's Sat Aug 1 high anywhere from 20° to 30°; by the final call the field had settled to a median of 29°. The day verified at 30° against the ECMWF IFS analysis, with 0.8 mm of precipitation — drizzle.
GFS landed closest, off by 0.1°. AIFS ran 2° cold.
What every model said, at every lead
Daily-high calls for Sat Aug 1 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 |
|---|---|---|---|---|---|---|---|---|
| 5d · 2026-07-27 | 25° | 30° | 23° | 26° | 20° | 24° | 27° | 20–30° |
| 4d · 2026-07-28 | 26° | 30° | 26° | 28° | 21° | 26° | 27° | 21–30° |
| 3d · 2026-07-29 | 27° | 29° | 28° | 26° | 26° | 28° | 27° | 26–29° |
| 2d · 2026-07-30 | 26° | 29° | 28° | 28° | 28° | 27° | 30° | 26–30° |
| 1d · 2026-07-31 | 28° | 28° | 28° | 29° | 31° | 29° | 29° | 28–31° |
| 0d · 2026-08-01 | 28° | 30° | 28° | 29° | 30° | 29° | 30° | 28–30° |
| actual | 30° |
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.