Was the forecast right for Boston on Thu Jul 30?
Boston, Massachusetts · daily high temperature in °C · forecasts from each model's archived runs, verified against the ECMWF IFS analysis
4 days out, 7 models put Boston's Thu Jul 30 high anywhere from 19° to 24°;by the final call, the day before, the field had settled to a median of 20°. The day verified at 23° against the ECMWF IFS analysis, with 13.2 mm of precipitation — rain.
ECMWF landed closest, off by 2.2°. AIGFS ran 4° cool.
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 |
|---|---|---|---|---|---|---|---|---|
| 4d · 2026-07-26 | 21° | 21° | 21° | 20° | 21° | 24° | 19° | 19–24° |
| 3d · 2026-07-27 | 20° | 19° | 24° | 19° | 19° | 20° | 20° | 19–24° |
| 2d · 2026-07-28 | 20° | 20° | 20° | 20° | 20° | 20° | 18° | 18–20° |
| 1d · 2026-07-29 | 20° | 19° | 21° | 19° | 19° | 20° | 20° | 19–21° |
| actual | 23° |
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.