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

Houston Bush · NCEP GFS · lead day 9

KIAH · gfs · lead 9

Target day = initialization date + 9 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
tmax00Zbilinear30d21 1 QC2.87 [1.23, 4.69]2.93-1.23 [-3.88, 1.97]4.77 [1.54, 6.66]43% [14%, 68%]67%71%+0.14+0.052026-08-10 → 2026-08-30
tmax00Zbilinear90d21 1 QC2.87 [1.13, 5.22]2.93-1.23 [-3.98, 2.72]4.77 [1.53, 7.02]43% [10%, 70%]67%71%+0.14+0.052026-08-10 → 2026-08-30
tmax00Zbilinear365d21 1 QC2.87 [1.03, 5.27]2.93-1.23 [-4.58, 2.50]4.77 [1.49, 7.02]43% [11%, 71%]67%71%+0.14+0.052026-08-10 → 2026-08-30
tmax00Zbilinearall21 1 QC2.87 [1.04, 5.27]2.93-1.23 [-4.69, 2.63]4.77 [1.50, 7.02]43% [10%, 71%]67%71%+0.14+0.052026-08-10 → 2026-08-30
tmax00Znearest30d21 1 QC3.05 [1.27, 4.94]3.14-1.46 [-4.17, 1.75]5.02 [1.86, 6.99]43% [6%, 71%]62%67%+0.09-0.022026-08-10 → 2026-08-30
tmax00Znearest90d21 1 QC3.05 [1.19, 5.44]3.14-1.46 [-4.48, 2.62]5.02 [1.61, 7.41]43% [0%, 71%]62%67%+0.09-0.022026-08-10 → 2026-08-30
tmax00Znearest365d21 1 QC3.05 [1.00, 5.50]3.14-1.46 [-4.87, 2.35]5.02 [1.51, 7.41]43% [0%, 73%]62%67%+0.09-0.022026-08-10 → 2026-08-30
tmax00Znearestall21 1 QC3.05 [1.07, 5.53]3.14-1.46 [-5.08, 2.51]5.02 [1.51, 7.44]43% [0%, 71%]62%67%+0.09-0.022026-08-10 → 2026-08-30
tmax12Zbilinear30d21 1 QC2.50 [1.46, 3.66]2.42-0.73 [-2.75, 1.59]3.32 [1.81, 4.54]29% [11%, 45%]62%67%+0.25+0.222026-08-10 → 2026-08-30
tmax12Zbilinear90d21 1 QC2.50 [1.39, 3.86]2.42-0.73 [-2.74, 1.99]3.32 [1.73, 4.59]29% [6%, 48%]62%67%+0.25+0.222026-08-10 → 2026-08-30
tmax12Zbilinear365d21 1 QC2.50 [1.40, 4.00]2.42-0.73 [-2.97, 1.96]3.32 [1.71, 4.75]29% [3%, 50%]62%67%+0.25+0.222026-08-10 → 2026-08-30
tmax12Zbilinearall21 1 QC2.50 [1.39, 4.01]2.42-0.73 [-3.26, 1.96]3.32 [1.72, 4.77]29% [6%, 50%]62%67%+0.25+0.222026-08-10 → 2026-08-30
tmax12Znearest30d21 1 QC2.48 [1.47, 3.61]2.39-0.69 [-2.65, 1.54]3.17 [1.79, 4.29]29% [0%, 50%]52%71%+0.26+0.222026-08-10 → 2026-08-30
tmax12Znearest90d21 1 QC2.48 [1.41, 3.76]2.39-0.69 [-2.67, 2.06]3.17 [1.69, 4.38]29% [0%, 53%]52%71%+0.26+0.222026-08-10 → 2026-08-30
tmax12Znearest365d21 1 QC2.48 [1.38, 3.86]2.39-0.69 [-2.84, 1.93]3.17 [1.66, 4.50]29% [0%, 54%]52%71%+0.26+0.222026-08-10 → 2026-08-30
tmax12Znearestall21 1 QC2.48 [1.37, 3.87]2.39-0.69 [-3.27, 1.94]3.17 [1.65, 4.52]29% [0%, 55%]52%71%+0.26+0.222026-08-10 → 2026-08-30
tmin00Zbilinear30d21 1 QC3.55 [2.27, 5.04]2.79+3.10 [1.24, 4.99]4.39 [3.12, 5.53]24% [8%, 39%]43%48%+0.08+0.262026-08-10 → 2026-08-30
tmin00Zbilinear90d21 1 QC3.55 [2.22, 5.33]2.79+3.10 [1.17, 5.33]4.39 [3.03, 5.77]24% [0%, 41%]43%48%+0.08+0.262026-08-10 → 2026-08-30
tmin00Zbilinear365d21 1 QC3.55 [2.10, 5.29]2.79+3.10 [0.81, 5.29]4.39 [2.86, 5.67]24% [0%, 43%]43%48%+0.08+0.262026-08-10 → 2026-08-30
tmin00Zbilinearall21 1 QC3.55 [1.88, 5.33]2.79+3.10 [0.75, 5.33]4.39 [2.55, 5.63]24% [0%, 43%]43%48%+0.08+0.262026-08-10 → 2026-08-30
tmin00Znearest30d21 1 QC3.65 [2.50, 5.02]2.71+3.12 [1.30, 4.99]4.39 [3.22, 5.45]19% [7%, 29%]38%52%+0.05+0.282026-08-10 → 2026-08-30
tmin00Znearest90d21 1 QC3.65 [2.42, 5.31]2.71+3.12 [1.17, 5.31]4.39 [3.14, 5.69]19% [0%, 29%]38%52%+0.05+0.282026-08-10 → 2026-08-30
tmin00Znearest365d21 1 QC3.65 [2.32, 5.23]2.71+3.12 [0.81, 5.23]4.39 [2.99, 5.58]19% [0%, 29%]38%52%+0.05+0.282026-08-10 → 2026-08-30
tmin00Znearestall21 1 QC3.65 [2.11, 5.31]2.71+3.12 [0.75, 5.31]4.39 [2.72, 5.57]19% [0%, 29%]38%52%+0.05+0.282026-08-10 → 2026-08-30
tmin12Zbilinear30d21 1 QC3.70 [2.37, 5.23]3.01+2.87 [0.63, 5.08]4.47 [3.06, 5.70]19% [6%, 31%]29%48%+0.04+0.202026-08-10 → 2026-08-30
tmin12Zbilinear90d21 1 QC3.70 [2.37, 5.66]3.01+2.87 [0.58, 5.66]4.47 [3.04, 5.90]19% [0%, 30%]29%48%+0.04+0.202026-08-10 → 2026-08-30
tmin12Zbilinear365d21 1 QC3.70 [2.22, 5.61]3.01+2.87 [0.27, 5.59]4.47 [2.80, 5.94]19% [0%, 29%]29%48%+0.04+0.202026-08-10 → 2026-08-30
tmin12Zbilinearall21 1 QC3.70 [1.93, 5.64]3.01+2.87 [-0.16, 5.64]4.47 [2.38, 5.80]19% [0%, 32%]29%48%+0.04+0.202026-08-10 → 2026-08-30
tmin12Znearest30d21 1 QC3.84 [2.65, 5.31]3.22+2.74 [0.35, 5.11]4.63 [3.36, 5.87]19% [6%, 31%]33%43%+0.00+0.152026-08-10 → 2026-08-30
tmin12Znearest90d21 1 QC3.84 [2.63, 5.69]3.22+2.74 [0.25, 5.67]4.63 [3.33, 6.10]19% [0%, 30%]33%43%+0.00+0.152026-08-10 → 2026-08-30
tmin12Znearest365d21 1 QC3.84 [2.56, 5.66]3.22+2.74 [-0.04, 5.61]4.63 [3.17, 6.10]19% [0%, 29%]33%43%+0.00+0.152026-08-10 → 2026-08-30
tmin12Znearestall21 1 QC3.84 [2.28, 5.65]3.22+2.74 [-0.54, 5.65]4.63 [2.83, 5.95]19% [0%, 32%]33%43%+0.00+0.152026-08-10 → 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 KIAH, lead day 9, 00Z bilinear tmax+20+100-10-202026-08-10: +10.46 °F2026-08-11: +0.39 °F2026-08-12: -0.09 °F2026-08-13: -0.4 °F2026-08-14: +3.17 °F2026-08-15: +0.04 °F2026-08-16: -0.41 °F2026-08-17: -2.45 °F2026-08-18: -0.07 °F2026-08-19: -0.55 °F2026-08-20: -0.59 °F2026-08-21: -1.22 °F2026-08-22: -7.61 °F2026-08-23: -14.77 °F2026-08-24: -6.27 °F2026-08-25: -5.02 °F2026-08-26: -1.58 °F2026-08-27: -0.39 °F2026-08-28: -1.65 °F2026-08-29: +1.71 °F2026-08-30: +1.44 °F2026-08-102026-08-30°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 (21 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+1.44
2026-08-29+1.71
2026-08-28-1.65
2026-08-27-0.39
2026-08-26-1.58
2026-08-25-5.02
2026-08-24-6.27
2026-08-23-14.77
2026-08-22-7.61
2026-08-21-1.22
2026-08-20-0.59
2026-08-19-0.55
2026-08-18-0.07
2026-08-17-2.45
2026-08-16-0.41
2026-08-15+0.04
2026-08-14+3.17
2026-08-13-0.40
2026-08-12-0.09
2026-08-11+0.39
2026-08-10+10.46

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KIAH, lead day 9-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 1 day-14 to -12 °F: 0 days-12 to -10 °F: 0 days-10 to -8 °F: 0 days-8 to -6 °F: 2 days-6 to -4 °F: 1 day-4 to -2 °F: 1 day-2 to 0 °F: 10 days0 to 2 °F: 4 days2 to 4 °F: 1 day4 to 6 °F: 0 days6 to 8 °F: 0 days8 to 10 °F: 0 days10 to 12 °F: 1 day12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 1.44 · P90 |e| 7.61 °F-200+20 °Fn = 21 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
-20.00-18.000
-18.00-16.000
-16.00-14.001
-14.00-12.000
-12.00-10.000
-10.00-8.000
-8.00-6.002
-6.00-4.001
-4.00-2.001
-2.00+0.0010
+0.00+2.004
+2.00+4.001
+4.00+6.000
+6.00+8.000
+8.00+10.000
+10.00+12.001
+12.00+14.000
+14.00+16.000
+16.00+18.000
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08212.87 -1.23

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21

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 21 -0.89 [-2.24, 1.06] no
GraphCast (IFS init) 21 -3.51 [-5.41, -0.65] yes
ECMWF IFS HRES 16 -0.33 [-2.14, 5.83] no
Persistence (baseline) 21 -0.46 [-2.64, 1.76] no

Cite this page

ShortCastCheck, KIAH gfs lead 9, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KIAH/model/gfs/lead/9/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KIAH (Houston Bush), model gfs, lead day 9. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KIAH/model/gfs/lead/9/

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