Was the forecast right for Boston on Thu Jul 30?
Boston, Massachusetts · daily high temperature · forecasts from each model's archived runs, verified against ERA5
3 days out, 7 models put Boston's Thu Jul 30 high anywhere from 67° to 73°; by the final call the field had settled to a median of 68°. ERA5 says the day verified at 73° with 0.52 in of precipitation — rain.
GEM landed closest, off by 2.6°. AIGFS ran 8° cold.
What every model said, at every lead
Daily-high calls for Thu Jul 30 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 |
|---|---|---|---|---|---|---|---|---|
| 3d · 2026-07-27 | 69° | 70° | 73° | 69° | 68° | 67° | 68° | 67–73° |
| 2d · 2026-07-28 | 69° | 66° | 73° | 68° | 67° | 67° | 66° | 66–73° |
| 1d · 2026-07-29 | 67° | 66° | 68° | 67° | 67° | 67° | 67° | 66–68° |
| 0d · 2026-07-30 | 68° | 65° | 69° | 71° | 68° | 68° | 68° | 65–71° |
| actual | 73° |
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.