Was the forecast right for Phoenix on Sun Sep 13?
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 Sun Sep 13 high anywhere from 85° to 95°; by the final call the field had settled to a median of 101°. The day verified at 105° against the PHX observations — thunderstorms.
GEM landed closest, off by 3.5°. ICON ran 8° cold.
What every model said, at every lead
Daily-high calls for Sun Sep 13 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 · 2026-08-29 | — | 97° | — | — | 98° | — | — | 97–98° |
| 14d · 2026-08-30 | 100° | 105° | — | — | 107° | — | — | 100–107° |
| 13d · 2026-08-31 | 95° | 91° | 85° | — | 93° | — | — | 85–95° |
| 12d · 2026-09-01 | 85° | 93° | 89° | — | 93° | — | — | 85–93° |
| 11d · 2026-09-02 | 84° | 82° | 91° | — | 95° | — | — | 82–95° |
| 10d · 2026-09-03 | 108° | 92° | 102° | — | 98° | — | — | 92–108° |
| 9d · 2026-09-04 | 102° | 97° | 92° | — | 103° | — | — | 92–103° |
| 8d · 2026-09-05 | 103° | 101° | 93° | 106° | 96° | — | — | 93–106° |
| 7d · 2026-09-06 | 105° | 98° | 94° | 106° | 101° | — | — | 94–106° |
| 6d · 2026-09-07 | 103° | 104° | 100° | 96° | 102° | 105° | — | 96–105° |
| 5d · 2026-09-08 | 103° | 106° | 103° | 108° | 100° | 94° | 101° | 94–108° |
| 4d · 2026-09-09 | 103° | 103° | 102° | 104° | 104° | 91° | 101° | 91–104° |
| 3d · 2026-09-10 | 102° | 101° | 102° | 107° | 104° | 98° | 101° | 98–107° |
| 2d · 2026-09-11 | 102° | 101° | 104° | 104° | 102° | 98° | 103° | 98–104° |
| 1d · 2026-09-12 | 99° | 100° | 99° | 102° | 102° | 97° | 103° | 97–103° |
| 0d · 2026-09-13 | 101° | 100° | 100° | 102° | 101° | 97° | 101° | 97–102° |
| actual | 105° |
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.