Was the forecast right for Phoenix on Tue Sep 1?
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 Tue Sep 1 high anywhere from 39° to 40°;by the final call, the day before, the field had settled to a median of 37°. The day verified at 38° against the PHX observations — drizzle.
GFS landed closest, off by 0.0°. ECMWF ran 4° cool.
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 Phoenix scoreboard shows them, labelled.
| Lead | AIFS | AIGFS | ECMWF | GEM | GFS | ICON | UKMO | Range |
|---|---|---|---|---|---|---|---|---|
| 13d · 2026-08-19 | 39° | 39° | 40° | — | 40° | — | — | 39–40° |
| 12d · 2026-08-20 | 38° | 35° | 41° | — | 42° | — | — | 35–42° |
| 11d · 2026-08-21 | 40° | 39° | 42° | — | 42° | — | — | 39–42° |
| 10d · 2026-08-22 | 40° | 41° | 44° | — | 40° | — | — | 40–44° |
| 9d · 2026-08-23 | 39° | 38° | 42° | 40° | 44° | — | — | 38–44° |
| 8d · 2026-08-24 | 39° | 36° | 38° | 37° | 38° | — | — | 36–39° |
| 7d · 2026-08-25 | 38° | 38° | 40° | 38° | 40° | — | — | 38–40° |
| 6d · 2026-08-26 | 39° | 37° | 40° | 38° | 37° | 37° | 40° | 37–40° |
| 5d · 2026-08-27 | 38° | 38° | 36° | 38° | 38° | 40° | 40° | 36–40° |
| 4d · 2026-08-28 | 37° | 37° | 38° | 36° | 38° | 37° | 41° | 36–41° |
| 3d · 2026-08-29 | 36° | 38° | 37° | 36° | 38° | 36° | 39° | 36–39° |
| 2d · 2026-08-30 | 37° | 37° | 38° | 37° | 38° | 36° | 37° | 36–38° |
| 1d · 2026-08-31 | 35° | 37° | 34° | 38° | 38° | 37° | 36° | 34–38° |
| actual | 38° |
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. 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.