Was the forecast right for Boston on Sat Aug 1?
Boston, Massachusetts · daily high temperature · forecasts from each model's archived runs, verified against ERA5
5 days out, 7 models put Boston's Sat Aug 1 high anywhere from 67° to 86°; by the final call the field had settled to a median of 85°. ERA5 says the day verified at 86° with 0.03 in of precipitation — drizzle.
GFS landed closest, off by 0.1°. AIFS ran 4° 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 | 78° | 86° | 73° | 78° | 67° | 75° | 81° | 67–86° |
| 4d · 2026-07-28 | 79° | 86° | 79° | 82° | 70° | 80° | 80° | 70–86° |
| 3d · 2026-07-29 | 80° | 84° | 83° | 79° | 79° | 83° | 81° | 79–84° |
| 2d · 2026-07-30 | 79° | 84° | 82° | 82° | 82° | 81° | 86° | 79–86° |
| 1d · 2026-07-31 | 82° | 82° | 83° | 85° | 87° | 84° | 84° | 82–87° |
| 0d · 2026-08-01 | 82° | 85° | 83° | 84° | 86° | 85° | 86° | 82–86° |
| actual | 86° |
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 ERA5 reanalysis (temperature_2m_max). Archive depth varies by city; receipts exist only for dates the archive watched arrive.