Was the forecast right for Boston on Tue Sep 1?
Boston, Massachusetts · daily high temperature in °F · forecasts from each model's archived runs, verified against the BOS observations
13 days out, 4 models put Boston's Tue Sep 1 high anywhere from 70° to 87°;by the final call, the day before, the field had settled to a median of 69°. The day verified at 69° against the BOS observations, with 0.26 in of precipitation — showers.
ICON landed closest, off by 0.1°. UKMO ran 4° warm.
What every model said, at every lead
Daily-high calls for Tue Sep 1 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 |
|---|---|---|---|---|---|---|---|---|
| 13d · 2026-08-19 | 76° | 87° | 76° | — | 70° | — | — | 70–87° |
| 12d · 2026-08-20 | 71° | 92° | 84° | — | 89° | — | — | 71–92° |
| 11d · 2026-08-21 | 79° | 89° | 72° | — | 84° | — | — | 72–89° |
| 10d · 2026-08-22 | 72° | 73° | 73° | — | 72° | — | — | 72–73° |
| 9d · 2026-08-23 | 77° | 73° | 71° | 84° | 70° | — | — | 70–84° |
| 8d · 2026-08-24 | 76° | 91° | 75° | 78° | 75° | — | — | 75–91° |
| 7d · 2026-08-25 | 81° | 88° | 90° | 73° | 66° | — | — | 66–90° |
| 6d · 2026-08-26 | 74° | 70° | 79° | 74° | 69° | 73° | 90° | 69–90° |
| 5d · 2026-08-27 | 74° | 69° | 76° | 71° | 66° | 76° | 76° | 66–76° |
| 4d · 2026-08-28 | 74° | 74° | 71° | 70° | 72° | 77° | 80° | 70–80° |
| 3d · 2026-08-29 | 70° | 68° | 80° | 71° | 69° | 70° | 70° | 68–80° |
| 2d · 2026-08-30 | 67° | 66° | 71° | 70° | 68° | 69° | 71° | 66–71° |
| 1d · 2026-08-31 | 68° | 66° | 72° | 71° | 68° | 69° | 73° | 66–73° |
| actual | 69° |
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. 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.