Was the forecast right for Boston on Fri Jul 31?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
5 days out, 7 models put Boston's Fri Jul 31 high anywhere from 68° to 79°;by the final call, the day before, the field had settled to a median of 76°. The day verified at 76° against the ECMWF IFS analysis, with 0.1 in of precipitation — drizzle.
AIFS landed closest, off by 0.1°. GFS ran 5° warm.
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 |
|---|---|---|---|---|---|---|---|---|
| 5d · 2026-07-26 | 72° | 77° | 79° | 68° | 69° | 76° | 76° | 68–79° |
| 4d · 2026-07-27 | 76° | 80° | 72° | 70° | 67° | 70° | 73° | 67–80° |
| 3d · 2026-07-28 | 74° | 76° | 72° | 76° | 67° | 71° | 74° | 67–76° |
| 2d · 2026-07-29 | 75° | 76° | 77° | 75° | 74° | 77° | 80° | 74–80° |
| 1d · 2026-07-30 | 76° | 77° | 76° | 77° | 81° | 75° | 76° | 75–81° |
| 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 the ECMWF IFS analysis (temperature_2m_max). The actual values are the ones in hand when this receipt was settled, usually 2 days after the date; a correction published after that is not carried into it. Archive depth varies by city; receipts exist only for dates the archive watched arrive.