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 5

KPHX · gfs · lead 5

Target day = initialization date + 5 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
tmax00Zbilinear30d25 1 QC4.01 [2.76, 5.13]2.63-3.45 [-4.41, -2.36]4.67 [3.48, 5.55]20% [4%, 36%]28%36%+0.26+0.522026-08-06 → 2026-08-30
tmax00Zbilinear90d25 1 QC4.01 [2.60, 5.25]2.63-3.45 [-4.48, -2.15]4.67 [3.24, 5.60]20% [4%, 38%]28%36%+0.26+0.522026-08-06 → 2026-08-30
tmax00Zbilinear365d25 1 QC4.01 [2.54, 5.32]2.63-3.45 [-4.66, -2.14]4.67 [3.22, 5.68]20% [0%, 39%]28%36%+0.26+0.522026-08-06 → 2026-08-30
tmax00Zbilinearall25 1 QC4.01 [2.55, 5.38]2.63-3.45 [-4.61, -2.17]4.67 [3.23, 5.68]20% [0%, 40%]28%36%+0.26+0.522026-08-06 → 2026-08-30
tmax00Znearest30d25 1 QC3.91 [2.67, 5.04]2.64-3.31 [-4.26, -2.22]4.56 [3.38, 5.43]20% [4%, 36%]28%36%+0.28+0.522026-08-06 → 2026-08-30
tmax00Znearest90d25 1 QC3.91 [2.52, 5.13]2.64-3.31 [-4.36, -2.01]4.56 [3.16, 5.50]20% [4%, 38%]28%36%+0.28+0.522026-08-06 → 2026-08-30
tmax00Znearest365d25 1 QC3.91 [2.48, 5.23]2.64-3.31 [-4.51, -2.00]4.56 [3.14, 5.54]20% [0%, 39%]28%36%+0.28+0.522026-08-06 → 2026-08-30
tmax00Znearestall25 1 QC3.91 [2.48, 5.28]2.64-3.31 [-4.46, -2.03]4.56 [3.16, 5.54]20% [0%, 40%]28%36%+0.28+0.522026-08-06 → 2026-08-30
tmax12Zbilinear30d25 1 QC4.79 [3.81, 6.06]2.71-4.40 [-5.70, -3.57]5.61 [4.38, 7.14]12% [0%, 26%]20%28%+0.12+0.502026-08-06 → 2026-08-30
tmax12Zbilinear90d25 1 QC4.79 [3.74, 6.41]2.71-4.40 [-5.95, -3.54]5.61 [4.27, 7.53]12% [0%, 28%]20%28%+0.12+0.502026-08-06 → 2026-08-30
tmax12Zbilinear365d25 1 QC4.79 [3.70, 6.35]2.71-4.40 [-6.10, -3.50]5.61 [4.23, 7.57]12% [0%, 29%]20%28%+0.12+0.502026-08-06 → 2026-08-30
tmax12Zbilinearall25 1 QC4.79 [3.66, 6.47]2.71-4.40 [-6.16, -3.51]5.61 [4.20, 7.74]12% [0%, 27%]20%28%+0.12+0.502026-08-06 → 2026-08-30
tmax12Znearest30d25 1 QC4.70 [3.82, 5.78]2.64-4.26 [-5.34, -3.52]5.42 [4.40, 6.59]8% [0%, 24%]20%28%+0.14+0.512026-08-06 → 2026-08-30
tmax12Znearest90d25 1 QC4.70 [3.74, 6.12]2.64-4.26 [-5.60, -3.52]5.42 [4.30, 6.98]8% [0%, 25%]20%28%+0.14+0.512026-08-06 → 2026-08-30
tmax12Znearest365d25 1 QC4.70 [3.70, 6.06]2.64-4.26 [-5.65, -3.47]5.42 [4.25, 6.97]8% [0%, 29%]20%28%+0.14+0.512026-08-06 → 2026-08-30
tmax12Znearestall25 1 QC4.70 [3.68, 6.15]2.64-4.26 [-5.70, -3.49]5.42 [4.24, 7.07]8% [0%, 25%]20%28%+0.14+0.512026-08-06 → 2026-08-30
tmin00Zbilinear30d25 1 QC4.57 [3.09, 5.83]3.25+3.68 [0.93, 5.59]5.88 [3.57, 7.50]8% [0%, 19%]24%36%+0.18+0.422026-08-06 → 2026-08-30
tmin00Zbilinear90d25 1 QC4.57 [2.82, 5.98]3.25+3.68 [0.26, 5.91]5.88 [3.35, 7.58]8% [0%, 20%]24%36%+0.18+0.422026-08-06 → 2026-08-30
tmin00Zbilinear365d25 1 QC4.57 [2.81, 6.06]3.25+3.68 [0.28, 6.05]5.88 [3.30, 7.72]8% [0%, 21%]24%36%+0.18+0.422026-08-06 → 2026-08-30
tmin00Zbilinearall25 1 QC4.57 [2.79, 5.99]3.25+3.68 [0.07, 5.92]5.88 [3.26, 7.63]8% [0%, 22%]24%36%+0.18+0.422026-08-06 → 2026-08-30
tmin00Znearest30d25 1 QC5.54 [3.86, 6.91]3.31+4.81 [1.89, 6.82]6.74 [4.60, 8.38]8% [0%, 17%]16%28%+0.01+0.412026-08-06 → 2026-08-30
tmin00Znearest90d25 1 QC5.54 [3.39, 7.11]3.31+4.81 [1.10, 7.06]6.74 [4.10, 8.52]8% [0%, 17%]16%28%+0.01+0.412026-08-06 → 2026-08-30
tmin00Znearest365d25 1 QC5.54 [3.50, 7.19]3.31+4.81 [1.18, 7.19]6.74 [4.17, 8.64]8% [0%, 17%]16%28%+0.01+0.412026-08-06 → 2026-08-30
tmin00Znearestall25 1 QC5.54 [3.42, 7.14]3.31+4.81 [1.06, 7.13]6.74 [4.08, 8.51]8% [0%, 17%]16%28%+0.01+0.412026-08-06 → 2026-08-30
tmin12Zbilinear30d25 1 QC3.85 [2.60, 4.98]2.96+2.69 [0.31, 4.37]4.93 [3.16, 6.44]12% [3%, 25%]32%48%+0.31+0.472026-08-06 → 2026-08-30
tmin12Zbilinear90d25 1 QC3.85 [2.35, 5.14]2.96+2.69 [-0.19, 4.47]4.93 [2.84, 6.61]12% [0%, 30%]32%48%+0.31+0.472026-08-06 → 2026-08-30
tmin12Zbilinear365d25 1 QC3.85 [2.39, 5.20]2.96+2.69 [-0.35, 4.68]4.93 [2.96, 6.74]12% [0%, 29%]32%48%+0.31+0.472026-08-06 → 2026-08-30
tmin12Zbilinearall25 1 QC3.85 [2.35, 5.35]2.96+2.69 [-0.69, 4.43]4.93 [2.88, 6.68]12% [0%, 27%]32%48%+0.31+0.472026-08-06 → 2026-08-30
tmin12Znearest30d25 1 QC4.56 [3.30, 5.72]2.90+3.79 [1.46, 5.44]5.57 [3.73, 7.18]12% [0%, 24%]20%32%+0.19+0.482026-08-06 → 2026-08-30
tmin12Znearest90d25 1 QC4.56 [2.98, 5.84]2.90+3.79 [0.93, 5.55]5.57 [3.28, 7.29]12% [0%, 25%]20%32%+0.19+0.482026-08-06 → 2026-08-30
tmin12Znearest365d25 1 QC4.56 [2.96, 5.93]2.90+3.79 [0.79, 5.80]5.57 [3.34, 7.46]12% [0%, 27%]20%32%+0.19+0.482026-08-06 → 2026-08-30
tmin12Znearestall25 1 QC4.56 [2.96, 5.90]2.90+3.79 [0.46, 5.53]5.57 [3.27, 7.32]12% [0%, 27%]20%32%+0.19+0.482026-08-06 → 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 5, 00Z bilinear tmax+10+50-5-102026-08-06: +0.54 °F2026-08-07: -4.66 °F2026-08-08: -4.92 °F2026-08-09: -3.95 °F2026-08-10: -2.87 °F2026-08-11: -0.31 °F2026-08-12: -1.59 °F2026-08-13: -0.72 °F2026-08-14: -0.68 °F2026-08-15: -5.49 °F2026-08-16: -7.64 °F2026-08-17: -5.99 °F2026-08-18: -4.64 °F2026-08-19: -2.54 °F2026-08-20: +4.86 °F2026-08-21: -4.73 °F2026-08-22: -6.83 °F2026-08-23: -6.5 °F2026-08-24: -5.26 °F2026-08-25: -7.3 °F2026-08-26: -7.8 °F2026-08-27: -3.38 °F2026-08-28: +0.6 °F2026-08-29: -5.48 °F2026-08-30: +1.09 °F2026-08-062026-08-30°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 (25 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+1.09
2026-08-29-5.48
2026-08-28+0.60
2026-08-27-3.38
2026-08-26-7.80
2026-08-25-7.30
2026-08-24-5.26
2026-08-23-6.50
2026-08-22-6.83
2026-08-21-4.73
2026-08-20+4.86
2026-08-19-2.54
2026-08-18-4.64
2026-08-17-5.99
2026-08-16-7.64
2026-08-15-5.49
2026-08-14-0.68
2026-08-13-0.72
2026-08-12-1.59
2026-08-11-0.31
2026-08-10-2.87
2026-08-09-3.95
2026-08-08-4.92
2026-08-07-4.66
2026-08-06+0.54

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KPHX, lead day 5-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 3 days-7 to -6 °F: 2 days-6 to -5 °F: 4 days-5 to -4 °F: 4 days-4 to -3 °F: 2 days-3 to -2 °F: 2 days-2 to -1 °F: 1 day-1 to 0 °F: 3 days0 to 1 °F: 2 days1 to 2 °F: 1 day2 to 3 °F: 0 days3 to 4 °F: 0 days4 to 5 °F: 1 day5 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| 4.66 · P90 |e| 7.11 °F-100+10 °Fn = 25 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
-9.00-8.000
-8.00-7.003
-7.00-6.002
-6.00-5.004
-5.00-4.004
-4.00-3.002
-3.00-2.002
-2.00-1.001
-1.00+0.003
+0.00+1.002
+1.00+2.001
+2.00+3.000
+3.00+4.000
+4.00+5.001
+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
2026-08254.01 -3.45

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25

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 25 -0.12 [-2.08, 1.25] no
GraphCast (IFS init) 25 -1.05 [-2.48, -0.16] yes
ECMWF IFS HRES 18 +0.55 [-2.92, 2.10] no
Persistence (baseline) 25 -1.43 [-4.02, 1.03] no

Cite this page

ShortCastCheck, KPHX gfs lead 5, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KPHX/model/gfs/lead/5/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KPHX (Phoenix Sky Harbor), model gfs, lead day 5. 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/5/

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