Was the forecast right for Phoenix on Mon Sep 21?
Phoenix, Arizona · daily high temperature in °F · forecasts from each model's archived runs, verified against the PHX observations
14 days out, 4 models put Phoenix's Mon Sep 21 high anywhere from 95° to 100°;by the final call, the day before, the field had settled to a median of 99°. The day verified at 102° against the PHX observations — cloudy.
UKMO landed closest, off by 0.5°. ICON ran 5° cool.
What every model said, at every lead
Daily-high calls for Mon Sep 21 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 · 2026-09-06 | — | 100° | — | — | 96° | — | — | 96–100° |
| 14d · 2026-09-07 | 99° | 95° | 100° | — | 97° | — | — | 95–100° |
| 13d · 2026-09-08 | 101° | 100° | 104° | — | 99° | — | — | 99–104° |
| 12d · 2026-09-09 | 97° | 102° | 104° | — | 102° | — | — | 97–104° |
| 11d · 2026-09-10 | 100° | 99° | 93° | — | 90° | — | — | 90–100° |
| 10d · 2026-09-11 | 97° | 96° | 97° | — | 103° | — | — | 96–103° |
| 9d · 2026-09-12 | 99° | 95° | 102° | 100° | 102° | — | — | 95–102° |
| 8d · 2026-09-13 | 96° | 98° | 97° | 95° | 99° | — | — | 95–99° |
| 7d · 2026-09-14 | 100° | 97° | 101° | 95° | 94° | — | — | 94–101° |
| 6d · 2026-09-15 | 92° | 95° | 99° | 97° | 99° | 99° | 99° | 92–99° |
| 5d · 2026-09-16 | 96° | 96° | 99° | 94° | 100° | 99° | 97° | 94–100° |
| 4d · 2026-09-17 | 98° | 97° | 99° | 98° | 99° | 99° | 100° | 97–100° |
| 3d · 2026-09-18 | 100° | 98° | 100° | 98° | 99° | 97° | 102° | 97–102° |
| 2d · 2026-09-19 | 101° | 98° | 99° | 98° | 100° | 99° | 99° | 98–101° |
| 1d · 2026-09-20 | 101° | 98° | 100° | 98° | 99° | 97° | 102° | 97–102° |
| 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.