The Spread

Was the forecast right for Phoenix on Fri Sep 4?

Phoenix, Arizona · daily high temperature in °C · forecasts from each model's archived runs, verified against the PHX observations

13 days out, 4 models put Phoenix's Fri Sep 4 high anywhere from 37° to 45°; by the final call the field had settled to a median of 38°. The day verified at 40° against the PHX observations — drizzle.

GFS landed closest, off by 0.7°. GEM ran 3° cold.

13 days out the models said 37–45; it hit 40. GFS led (off 0.7°C); GEM ran 3°C cold.
The shareable card for this receipt — what this page looks like pasted into a thread.

What every model said, at every lead

Daily-high calls for Fri Sep 4 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 AIFSAIGFSECMWFGEMGFSICONUKMO Range
15d · 2026-08-20 — 42° — — 39° — — 39–42°
14d · 2026-08-21 39° 37° — — 29° — — 29–39°
13d · 2026-08-22 44° 39° 37° — 45° — — 37–45°
12d · 2026-08-23 41° 39° 36° — 42° — — 36–42°
11d · 2026-08-24 42° 38° 40° — 39° — — 38–42°
10d · 2026-08-25 38° 35° 39° — 39° — — 35–39°
9d · 2026-08-26 39° 38° 39° — 40° — — 38–40°
8d · 2026-08-27 38° 39° 42° 41° 39° — — 38–42°
7d · 2026-08-28 43° 36° 41° 41° 38° — — 36–43°
6d · 2026-08-29 39° 39° 36° 40° 38° 38° — 36–40°
5d · 2026-08-30 39° 39° 34° 37° 37° 32° 40° 32–40°
4d · 2026-08-31 39° 36° 33° 38° 38° 35° 39° 33–39°
3d · 2026-09-01 39° 37° 37° 38° 37° 37° 37° 37–39°
2d · 2026-09-02 39° 37° 39° 37° 39° 37° 38° 37–39°
1d · 2026-09-03 38° 37° 39° 37° 39° 36° 38° 36–39°
0d · 2026-09-04 39° 38° 39° 37° 39° 38° 37° 37–39°
actual 40°

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.