Was the forecast right for Phoenix on Fri Sep 18?
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 Fri Sep 18 high anywhere from 93° to 107°; by the final call the field had settled to a median of 98°. The day verified at 102° against the PHX observations — partly cloudy.
AIFS landed closest, off by 0.7°. UKMO ran 4° cold.
What every model said, at every lead
Daily-high calls for Fri Sep 18 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 · 2026-09-03 | — | 100° | — | — | 103° | — | — | 100–103° |
| 14d · 2026-09-04 | 96° | 102° | — | — | 95° | — | — | 95–102° |
| 13d · 2026-09-05 | 93° | 99° | 106° | — | 107° | — | — | 93–107° |
| 12d · 2026-09-06 | 97° | 101° | 104° | — | 104° | — | — | 97–104° |
| 11d · 2026-09-07 | 96° | 98° | 99° | — | 102° | — | — | 96–102° |
| 10d · 2026-09-08 | 96° | 101° | 108° | — | 105° | — | — | 96–108° |
| 9d · 2026-09-09 | 102° | 98° | 103° | — | 102° | — | — | 98–103° |
| 8d · 2026-09-10 | 98° | 104° | 99° | 104° | 105° | — | — | 98–105° |
| 7d · 2026-09-11 | 99° | 103° | 101° | 98° | 105° | — | — | 98–105° |
| 6d · 2026-09-12 | 100° | 103° | 105° | 104° | 101° | 103° | — | 100–105° |
| 5d · 2026-09-13 | 100° | 101° | 101° | 102° | 100° | 101° | 102° | 100–102° |
| 4d · 2026-09-14 | 99° | 100° | 100° | 98° | 101° | 99° | 103° | 98–103° |
| 3d · 2026-09-15 | 98° | 100° | 96° | 98° | 100° | 101° | 100° | 96–101° |
| 2d · 2026-09-16 | 98° | 98° | 101° | 99° | 100° | 101° | 100° | 98–101° |
| 1d · 2026-09-17 | 98° | 98° | 93° | 99° | 99° | 100° | 97° | 93–100° |
| 0d · 2026-09-18 | 101° | 98° | 98° | 98° | 100° | 99° | 98° | 98–101° |
| 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.