Was the forecast right for Boston on Sun Aug 23?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
3 days out, 7 models put Boston's Sun Aug 23 high anywhere from 70° to 82°; by the final call the field had settled to a median of 74°. The day verified at 71° against the BOS observations, with 0.38 in of precipitation — showers.
GEM landed closest, off by 1.3°. UKMO ran 9° hot.
What every model said, at every lead
Daily-high calls for Sun Aug 23 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 · 2026-08-20 | 74° | 74° | 82° | 76° | 70° | 76° | 72° | 70–82° |
| 2d · 2026-08-21 | 73° | 76° | 80° | 74° | 70° | 72° | 76° | 70–80° |
| 1d · 2026-08-22 | 75° | 75° | 74° | 78° | 74° | 71° | 74° | 71–78° |
| 0d · 2026-08-23 | 74° | 74° | 74° | 72° | 73° | 75° | 80° | 72–80° |
| actual | 71° |
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 BOS observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.