Was the forecast right for Phoenix on Tue Sep 15?
Phoenix, Arizona · daily high temperature in °F · forecasts from each model's archived runs, verified against the PHX observations
13 days out, 4 models put Phoenix's Tue Sep 15 high anywhere from 87° to 101°; by the final call the field had settled to a median of 96°. The day verified at 102° against the PHX observations — drizzle.
GEM landed closest, off by 4.2°. ICON ran 9° cold.
What every model said, at every lead
Daily-high calls for Tue Sep 15 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 · 2026-08-31 | — | 98° | — | — | 94° | — | — | 94–98° |
| 14d · 2026-09-01 | 92° | 94° | — | — | 99° | — | — | 92–99° |
| 13d · 2026-09-02 | 93° | 96° | 87° | — | 101° | — | — | 87–101° |
| 12d · 2026-09-03 | 107° | 90° | 86° | — | 99° | — | — | 86–107° |
| 11d · 2026-09-04 | 97° | 93° | 89° | — | 100° | — | — | 89–100° |
| 10d · 2026-09-05 | 95° | 98° | 88° | — | 101° | — | — | 88–101° |
| 9d · 2026-09-06 | 87° | 96° | 99° | — | 101° | — | — | 87–101° |
| 8d · 2026-09-07 | 90° | 100° | 86° | 102° | 95° | — | — | 86–102° |
| 7d · 2026-09-08 | 96° | 99° | 100° | 97° | 100° | — | — | 96–100° |
| 6d · 2026-09-09 | 98° | 97° | 100° | 91° | 97° | 91° | — | 91–100° |
| 5d · 2026-09-10 | 98° | 96° | 98° | 93° | 97° | 88° | 98° | 88–98° |
| 4d · 2026-09-11 | 91° | 95° | 101° | 98° | 94° | 89° | 102° | 89–102° |
| 3d · 2026-09-12 | 93° | 95° | 100° | 99° | 97° | 93° | 100° | 93–100° |
| 2d · 2026-09-13 | 93° | 94° | 96° | 100° | 101° | 97° | 104° | 93–104° |
| 1d · 2026-09-14 | 96° | 95° | 98° | 100° | 100° | 94° | 100° | 94–100° |
| 0d · 2026-09-15 | 95° | 96° | 97° | 98° | 97° | 93° | 96° | 93–98° |
| actual | 102° |
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.