Was the forecast right for Boston on Fri Jul 31?
Boston, Massachusetts · daily high temperature · forecasts from each model's archived runs, verified against ERA5
4 days out, 7 models put Boston's Fri Jul 31 high anywhere from 68° to 84°; by the final call the field had settled to a median of 78°. ERA5 says the day verified at 76° with 0.1 in of precipitation — drizzle.
ICON landed closest, off by 0.1°. GFS ran 6° hot.
What every model said, at every lead
Daily-high calls for Fri Jul 31 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 |
|---|---|---|---|---|---|---|---|---|
| 4d · 2026-07-27 | 72° | 81° | 70° | 68° | 68° | 73° | 84° | 68–84° |
| 3d · 2026-07-28 | 73° | 81° | 70° | 76° | 69° | 78° | 75° | 69–81° |
| 2d · 2026-07-29 | 74° | 75° | 73° | 79° | 71° | 73° | 77° | 71–79° |
| 1d · 2026-07-30 | 75° | 77° | 78° | 78° | 79° | 79° | 82° | 75–82° |
| 0d · 2026-07-31 | 77° | 77° | 78° | 79° | 83° | 77° | 78° | 77–83° |
| actual | 76° |
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.