Was the forecast right for Phoenix on Sun Sep 6?
Phoenix, Arizona · daily high temperature in °C · forecasts from each model's archived runs, verified against the PHX observations
13 days out, 4 models put Phoenix's Sun Sep 6 high anywhere from 36° to 38°; by the final call the field had settled to a median of 40°. The day verified at 42° against the PHX observations — cloudy.
ECMWF landed closest, off by 1.2°. AIGFS ran 2° cold.
What every model said, at every lead
Daily-high calls for Sun Sep 6 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 Phoenix scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 15d · 2026-08-22 | — | 36° | — | — | 42° | — | — | 36–42° |
| 14d · 2026-08-23 | 37° | 39° | — | — | 42° | — | — | 37–42° |
| 13d · 2026-08-24 | 38° | 36° | 38° | — | 38° | — | — | 36–38° |
| 12d · 2026-08-25 | 40° | 39° | 37° | — | 36° | — | — | 36–40° |
| 11d · 2026-08-26 | 39° | 35° | 36° | — | 37° | — | — | 35–39° |
| 10d · 2026-08-27 | 38° | 38° | 35° | — | 35° | — | — | 35–38° |
| 9d · 2026-08-28 | 40° | 37° | 40° | — | 40° | — | — | 37–40° |
| 8d · 2026-08-29 | 40° | 42° | 38° | 39° | 38° | — | — | 38–42° |
| 7d · 2026-08-30 | 41° | 41° | 38° | 41° | 41° | — | — | 38–41° |
| 6d · 2026-08-31 | 38° | 38° | 34° | 38° | 36° | 35° | — | 34–38° |
| 5d · 2026-09-01 | 39° | 39° | 41° | 39° | 37° | 34° | 40° | 34–41° |
| 4d · 2026-09-02 | 40° | 39° | 40° | 39° | 39° | 40° | 40° | 39–40° |
| 3d · 2026-09-03 | 39° | 38° | 40° | 39° | 39° | 38° | 40° | 38–40° |
| 2d · 2026-09-04 | 39° | 39° | 41° | 38° | 39° | 38° | 39° | 38–41° |
| 1d · 2026-09-05 | 40° | 39° | 40° | 38° | 39° | 39° | 40° | 38–40° |
| 0d · 2026-09-06 | 40° | 39° | 40° | 40° | 40° | 39° | 39° | 39–40° |
| actual | 42° |
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 Phoenix — 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 PHX observations. Archive depth varies by city; receipts exist only for dates the archive watched arrive.