Was the forecast right for Phoenix on Sun Sep 20?
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 20 high anywhere from 88° to 106°; by the final call the field had settled to a median of 98°. The day verified at 104° against the PHX observations — cloudy.
ECMWF landed closest, off by 3.8°. AIGFS ran 7° cool.
What every model said, at every lead
Daily-high calls for Sun Sep 20 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 · 2026-09-05 | — | 98° | — | — | 106° | — | — | 98–106° |
| 14d · 2026-09-06 | 96° | 103° | — | — | 102° | — | — | 96–103° |
| 13d · 2026-09-07 | 96° | 88° | 100° | — | 106° | — | — | 88–106° |
| 12d · 2026-09-08 | 98° | 97° | 98° | — | 100° | — | — | 97–100° |
| 11d · 2026-09-09 | 101° | 102° | 103° | — | 104° | — | — | 101–104° |
| 10d · 2026-09-10 | 100° | 105° | 89° | — | 100° | — | — | 89–105° |
| 9d · 2026-09-11 | 100° | 100° | 98° | — | 101° | — | — | 98–101° |
| 8d · 2026-09-12 | 99° | 98° | 104° | 104° | 103° | — | — | 98–104° |
| 7d · 2026-09-13 | 98° | 101° | 97° | 101° | 102° | — | — | 97–102° |
| 6d · 2026-09-14 | 97° | 96° | 96° | 96° | 100° | 102° | — | 96–102° |
| 5d · 2026-09-15 | 96° | 98° | 100° | 98° | 100° | 103° | 98° | 96–103° |
| 4d · 2026-09-16 | 96° | 97° | 100° | 99° | 100° | 101° | 98° | 96–101° |
| 3d · 2026-09-17 | 96° | 96° | 95° | 99° | 99° | 100° | 96° | 95–100° |
| 2d · 2026-09-18 | 100° | 96° | 100° | 98° | 100° | 100° | 97° | 96–100° |
| 1d · 2026-09-19 | 100° | 97° | 101° | 98° | 98° | 99° | 97° | 97–101° |
| 0d · 2026-09-20 | 100° | 97° | 100° | 98° | 98° | 99° | 98° | 97–100° |
| actual | 104° |
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.