Raw model output on the native 0.25° grid — no MOS, no bias correction, no post-processing. Scores understate operational forecast quality. Read the fairness statement →

CastCheck methodology v0.2 · data through 2026-08-30

Phoenix Sky Harbor · NCEP GFS · lead day 7

KPHX · gfs · lead 7

Target day = initialization date + 7 days. This page is a permanent link: the numbers change as history accumulates, the address and the methodology version do not.

Scores use the latest model version segment, gfs-0p25, starting 2026-08-01 — days before that ran a different version of the model and are excluded rather than silently pooled. Of the scored days, 1 carry a QC flag on the observation.

JSON for this page CSV of the daily errors Cite this page

Every number for this combination

All four windows × both initializations × both interpolations × both variables. Errors are computed in °C and shown in °F; CI is a 95 % moving-block bootstrap interval. MAE debiased and skill, debiased remove the constant offset of the window first, so a station that the model always reads a degree too warm is not scored as if it had no skill — compare the two skill columns to see how much of the error is a fixed offset. n QC next to n counts days whose observation carries a QC flag.

VariableInitMethod Windown MAE °F MAE debiased Bias °F RMSE °F ±1 °F±2 °F±3 °F Skill Skill, debiased Period
tmax00Zbilinear30d23 1 QC4.31 [3.48, 5.30]2.93-3.87 [-5.02, -2.40]5.12 [4.23, 5.97]17% [8%, 27%]35%39%+0.19+0.462026-08-08 → 2026-08-30
tmax00Zbilinear90d23 1 QC4.31 [3.36, 5.42]2.93-3.87 [-5.40, -1.97]5.12 [4.00, 6.14]17% [7%, 28%]35%39%+0.19+0.462026-08-08 → 2026-08-30
tmax00Zbilinear365d23 1 QC4.31 [3.34, 5.55]2.93-3.87 [-5.43, -2.02]5.12 [4.05, 6.21]17% [5%, 29%]35%39%+0.19+0.462026-08-08 → 2026-08-30
tmax00Zbilinearall23 1 QC4.31 [3.38, 5.52]2.93-3.87 [-5.35, -1.91]5.12 [4.01, 6.12]17% [2%, 29%]35%39%+0.19+0.462026-08-08 → 2026-08-30
tmax00Znearest30d23 1 QC4.30 [3.46, 5.30]2.91-3.84 [-5.01, -2.35]5.07 [4.17, 5.95]17% [8%, 27%]39%39%+0.20+0.462026-08-08 → 2026-08-30
tmax00Znearest90d23 1 QC4.30 [3.33, 5.47]2.91-3.84 [-5.40, -1.95]5.07 [3.96, 6.16]17% [7%, 28%]39%39%+0.20+0.462026-08-08 → 2026-08-30
tmax00Znearest365d23 1 QC4.30 [3.32, 5.55]2.91-3.84 [-5.47, -2.04]5.07 [4.01, 6.22]17% [5%, 29%]39%39%+0.20+0.462026-08-08 → 2026-08-30
tmax00Znearestall23 1 QC4.30 [3.38, 5.50]2.91-3.84 [-5.37, -1.85]5.07 [4.00, 6.11]17% [2%, 29%]39%39%+0.20+0.462026-08-08 → 2026-08-30
tmax12Zbilinear30d23 1 QC4.99 [3.68, 6.17]3.51-4.73 [-6.05, -3.15]6.21 [4.90, 7.26]26% [6%, 44%]35%39%+0.07+0.352026-08-08 → 2026-08-30
tmax12Zbilinear90d23 1 QC4.99 [3.47, 6.46]3.51-4.73 [-6.35, -2.68]6.21 [4.60, 7.51]26% [0%, 45%]35%39%+0.07+0.352026-08-08 → 2026-08-30
tmax12Zbilinear365d23 1 QC4.99 [3.28, 6.55]3.51-4.73 [-6.49, -2.62]6.21 [4.39, 7.60]26% [0%, 46%]35%39%+0.07+0.352026-08-08 → 2026-08-30
tmax12Zbilinearall23 1 QC4.99 [3.42, 6.59]3.51-4.73 [-6.44, -2.52]6.21 [4.44, 7.69]26% [0%, 46%]35%39%+0.07+0.352026-08-08 → 2026-08-30
tmax12Znearest30d23 1 QC4.98 [3.70, 6.20]3.57-4.67 [-6.03, -3.06]6.19 [4.89, 7.23]26% [6%, 44%]35%43%+0.07+0.342026-08-08 → 2026-08-30
tmax12Znearest90d23 1 QC4.98 [3.43, 6.49]3.57-4.67 [-6.31, -2.58]6.19 [4.61, 7.48]26% [0%, 45%]35%43%+0.07+0.342026-08-08 → 2026-08-30
tmax12Znearest365d23 1 QC4.98 [3.26, 6.59]3.57-4.67 [-6.43, -2.51]6.19 [4.44, 7.51]26% [0%, 46%]35%43%+0.07+0.342026-08-08 → 2026-08-30
tmax12Znearestall23 1 QC4.98 [3.41, 6.59]3.57-4.67 [-6.40, -2.35]6.19 [4.45, 7.64]26% [0%, 46%]35%43%+0.07+0.342026-08-08 → 2026-08-30
tmin00Zbilinear30d23 1 QC4.38 [3.30, 5.30]3.62+2.85 [0.96, 4.19]5.23 [3.80, 6.13]9% [0%, 19%]26%43%+0.25+0.382026-08-08 → 2026-08-30
tmin00Zbilinear90d23 1 QC4.38 [3.11, 5.32]3.62+2.85 [0.56, 4.19]5.23 [3.67, 6.12]9% [0%, 20%]26%43%+0.25+0.382026-08-08 → 2026-08-30
tmin00Zbilinear365d23 1 QC4.38 [3.17, 5.34]3.62+2.85 [0.70, 4.24]5.23 [3.72, 6.14]9% [0%, 20%]26%43%+0.25+0.382026-08-08 → 2026-08-30
tmin00Zbilinearall23 1 QC4.38 [3.10, 5.33]3.62+2.85 [0.22, 4.28]5.23 [3.68, 6.12]9% [0%, 20%]26%43%+0.25+0.382026-08-08 → 2026-08-30
tmin00Znearest30d23 1 QC5.09 [3.92, 6.00]3.72+4.05 [2.09, 5.43]6.04 [4.53, 6.94]9% [0%, 17%]17%30%+0.13+0.362026-08-08 → 2026-08-30
tmin00Znearest90d23 1 QC5.09 [3.78, 5.99]3.72+4.05 [1.66, 5.44]6.04 [4.22, 6.96]9% [0%, 18%]17%30%+0.13+0.362026-08-08 → 2026-08-30
tmin00Znearest365d23 1 QC5.09 [3.77, 6.05]3.72+4.05 [1.86, 5.48]6.04 [4.34, 7.03]9% [0%, 19%]17%30%+0.13+0.362026-08-08 → 2026-08-30
tmin00Znearestall23 1 QC5.09 [3.73, 6.04]3.72+4.05 [1.39, 5.59]6.04 [4.24, 6.98]9% [0%, 17%]17%30%+0.13+0.362026-08-08 → 2026-08-30
tmin12Zbilinear30d23 1 QC4.88 [3.47, 6.15]4.40+3.42 [1.62, 4.92]6.18 [4.24, 7.34]13% [0%, 24%]30%43%+0.16+0.252026-08-08 → 2026-08-30
tmin12Zbilinear90d23 1 QC4.88 [3.36, 6.29]4.40+3.42 [1.10, 4.94]6.18 [3.94, 7.41]13% [0%, 25%]30%43%+0.16+0.252026-08-08 → 2026-08-30
tmin12Zbilinear365d23 1 QC4.88 [3.24, 6.31]4.40+3.42 [1.01, 5.16]6.18 [3.89, 7.48]13% [0%, 27%]30%43%+0.16+0.252026-08-08 → 2026-08-30
tmin12Zbilinearall23 1 QC4.88 [3.31, 6.34]4.40+3.42 [1.03, 5.05]6.18 [3.72, 7.39]13% [0%, 25%]30%43%+0.16+0.252026-08-08 → 2026-08-30
tmin12Znearest30d23 1 QC5.63 [4.29, 6.89]4.38+4.63 [2.84, 6.09]6.96 [5.01, 8.20]13% [0%, 24%]17%35%+0.03+0.252026-08-08 → 2026-08-30
tmin12Znearest90d23 1 QC5.63 [3.89, 6.92]4.38+4.63 [2.32, 6.14]6.96 [4.51, 8.24]13% [0%, 25%]17%35%+0.03+0.252026-08-08 → 2026-08-30
tmin12Znearest365d23 1 QC5.63 [3.93, 7.04]4.38+4.63 [2.20, 6.40]6.96 [4.60, 8.35]13% [0%, 27%]17%35%+0.03+0.252026-08-08 → 2026-08-30
tmin12Znearestall23 1 QC5.63 [3.87, 6.99]4.38+4.63 [2.23, 6.40]6.96 [4.43, 8.33]13% [0%, 25%]17%35%+0.03+0.252026-08-08 → 2026-08-30

+ model too warm · − model too cold · bias interval includes zero · ★ lowest MAE · = not distinguishable from the leader · ▼ significantly worse · n < 30 greyed and unranked · CI is a 95 % moving-block bootstrap interval.

Daily error, last 90 days

Daily forecast minus observed error in °F for NCEP GFS at KPHX, lead day 7, 00Z bilinear tmax+10+50-5-102026-08-08: -8.8 °F2026-08-09: -6.76 °F2026-08-10: -6.26 °F2026-08-11: -0.77 °F2026-08-12: -5.06 °F2026-08-13: -1.68 °F2026-08-14: +1.59 °F2026-08-15: -1.87 °F2026-08-16: -6.43 °F2026-08-17: -8.04 °F2026-08-18: -8.61 °F2026-08-19: -2.12 °F2026-08-20: -0.79 °F2026-08-21: -3.86 °F2026-08-22: -4.76 °F2026-08-23: -7.73 °F2026-08-24: -0.24 °F2026-08-25: -6.77 °F2026-08-26: -5.08 °F2026-08-27: -5.89 °F2026-08-28: -1.88 °F2026-08-29: -0.71 °F2026-08-30: +3.43 °F2026-08-082026-08-30°F, forecast − observed
Forecast − observed, °F, 00Z bilinear daily maximum. The dashed line is zero; the thick line is a centred 7-day mean, drawn only where the whole window is present. Gaps are days with no score, never interpolation. Hover a point for its date and value.
The same series as a table (23 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+3.43
2026-08-29-0.71
2026-08-28-1.88
2026-08-27-5.89
2026-08-26-5.08
2026-08-25-6.77
2026-08-24-0.24
2026-08-23-7.73
2026-08-22-4.76
2026-08-21-3.86
2026-08-20-0.79
2026-08-19-2.12
2026-08-18-8.61
2026-08-17-8.04
2026-08-16-6.43
2026-08-15-1.87
2026-08-14+1.59
2026-08-13-1.68
2026-08-12-5.06
2026-08-11-0.77
2026-08-10-6.26
2026-08-09-6.76
2026-08-08-8.80

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KPHX, lead day 7-10 to -9 °F: 0 days-9 to -8 °F: 3 days-8 to -7 °F: 1 day-7 to -6 °F: 4 days-6 to -5 °F: 3 days-5 to -4 °F: 1 day-4 to -3 °F: 1 day-3 to -2 °F: 1 day-2 to -1 °F: 3 days-1 to 0 °F: 4 days0 to 1 °F: 0 days1 to 2 °F: 1 day2 to 3 °F: 0 days3 to 4 °F: 1 day4 to 5 °F: 0 days5 to 6 °F: 0 days6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 4.76 · P90 |e| 7.98 °F-100+10 °Fn = 23 days
All scored days for 00Z bilinear daily maximum, 20 equal bins. The dashed marks are the 50th and 90th percentiles of the absolute error, mirrored on both sides. Hover a bar for its bin and count.
Bin counts as a table
From °FTo °FDays
-10.00-9.000
-9.00-8.003
-8.00-7.001
-7.00-6.004
-6.00-5.003
-5.00-4.001
-4.00-3.001
-3.00-2.001
-2.00-1.003
-1.00+0.004
+0.00+1.000
+1.00+2.001
+2.00+3.000
+3.00+4.001
+4.00+5.000
+5.00+6.000
+6.00+7.000
+7.00+8.000
+8.00+9.000
+9.00+10.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08234.31 -3.87

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means NCEP GFS has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 23 -1.20 [-3.27, 1.26] no
GraphCast (IFS init) 23 -2.63 [-5.67, -0.09] yes
ECMWF IFS HRES 18 +0.95 [-0.42, 3.10] no
Persistence (baseline) 23 -1.04 [-2.24, 0.82] no

Cite this page

ShortCastCheck, KPHX gfs lead 7, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KPHX/model/gfs/lead/7/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KPHX (Phoenix Sky Harbor), model gfs, lead day 7. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KPHX/model/gfs/lead/7/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

JSON CSV all scores methodology v0.2 licence