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
14 days out, 4 models put Phoenix's Sun Sep 6 high anywhere from 35° to 40°;by the final call, the day before, the field had settled to a median of 39°. The day verified at 42° against the PHX observations — cloudy.
ECMWF landed closest, off by 0.8°. GEM ran 3° cool.
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 | — | 35° | — | — | 40° | — | — | 35–40° |
| 14d · 2026-08-23 | 38° | 38° | 35° | — | 40° | — | — | 35–40° |
| 13d · 2026-08-24 | 39° | 35° | 37° | — | 40° | — | — | 35–40° |
| 12d · 2026-08-25 | 42° | 41° | 40° | — | 39° | — | — | 39–42° |
| 11d · 2026-08-26 | 40° | 38° | 39° | — | 40° | — | — | 38–40° |
| 10d · 2026-08-27 | 40° | 38° | 42° | — | 38° | — | — | 38–42° |
| 9d · 2026-08-28 | 39° | 41° | 43° | 39° | 36° | — | — | 36–43° |
| 8d · 2026-08-29 | 42° | 42° | 34° | 40° | 41° | — | — | 34–42° |
| 7d · 2026-08-30 | 41° | 41° | 38° | 39° | 36° | — | — | 36–41° |
| 6d · 2026-08-31 | 41° | 39° | 42° | 40° | 35° | 38° | 40° | 35–42° |
| 5d · 2026-09-01 | 41° | 40° | 41° | 39° | 38° | 39° | 39° | 38–41° |
| 4d · 2026-09-02 | 40° | 37° | 41° | 38° | 38° | 39° | 39° | 37–41° |
| 3d · 2026-09-03 | 39° | 38° | 40° | 39° | 39° | 38° | 40° | 38–40° |
| 2d · 2026-09-04 | 40° | 39° | 41° | 38° | 39° | 39° | 41° | 38–41° |
| 1d · 2026-09-05 | 39° | 39° | 41° | 38° | 40° | 39° | 40° | 38–41° |
| 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. 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.