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

San Antonio Intl · NCEP GFS · lead day 4

KSAT · gfs · lead 4

Target day = initialization date + 4 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
tmax00Zbilinear30d26 1 QC1.70 [1.11, 2.62]1.59-0.83 [-1.70, 0.02]2.28 [1.40, 3.24]50% [29%, 65%]69%81%+0.04+0.112026-08-05 → 2026-08-30
tmax00Zbilinear90d26 1 QC1.70 [1.09, 2.90]1.59-0.83 [-1.85, 0.09]2.28 [1.33, 3.51]50% [25%, 65%]69%81%+0.04+0.112026-08-05 → 2026-08-30
tmax00Zbilinear365d26 1 QC1.70 [1.04, 2.83]1.59-0.83 [-1.87, 0.13]2.28 [1.28, 3.43]50% [25%, 67%]69%81%+0.04+0.112026-08-05 → 2026-08-30
tmax00Zbilinearall26 1 QC1.70 [1.09, 2.87]1.59-0.83 [-1.91, 0.05]2.28 [1.37, 3.48]50% [22%, 67%]69%81%+0.04+0.112026-08-05 → 2026-08-30
tmax00Znearest30d26 1 QC1.60 [1.04, 2.54]1.57-0.51 [-1.38, 0.38]2.18 [1.33, 3.16]46% [33%, 57%]69%85%+0.10+0.122026-08-05 → 2026-08-30
tmax00Znearest90d26 1 QC1.60 [1.03, 2.80]1.57-0.51 [-1.50, 0.49]2.18 [1.28, 3.41]46% [31%, 58%]69%85%+0.10+0.122026-08-05 → 2026-08-30
tmax00Znearest365d26 1 QC1.60 [1.02, 2.70]1.57-0.51 [-1.54, 0.50]2.18 [1.26, 3.33]46% [31%, 58%]69%85%+0.10+0.122026-08-05 → 2026-08-30
tmax00Znearestall26 1 QC1.60 [1.04, 2.86]1.57-0.51 [-1.59, 0.49]2.18 [1.31, 3.39]46% [30%, 59%]69%85%+0.10+0.122026-08-05 → 2026-08-30
tmax12Zbilinear30d26 1 QC1.31 [0.97, 1.62]1.26-0.58 [-1.02, 0.10]1.74 [1.38, 2.01]46% [33%, 57%]77%88%+0.26+0.302026-08-05 → 2026-08-30
tmax12Zbilinear90d26 1 QC1.31 [0.96, 1.67]1.26-0.58 [-1.04, 0.28]1.74 [1.37, 2.04]46% [31%, 57%]77%88%+0.26+0.302026-08-05 → 2026-08-30
tmax12Zbilinear365d26 1 QC1.31 [0.93, 1.70]1.26-0.58 [-1.05, 0.34]1.74 [1.28, 2.06]46% [30%, 57%]77%88%+0.26+0.302026-08-05 → 2026-08-30
tmax12Zbilinearall26 1 QC1.31 [0.97, 1.71]1.26-0.58 [-1.08, 0.31]1.74 [1.35, 2.06]46% [28%, 57%]77%88%+0.26+0.302026-08-05 → 2026-08-30
tmax12Znearest30d26 1 QC1.28 [0.96, 1.59]1.27-0.34 [-0.81, 0.35]1.69 [1.32, 2.00]54% [36%, 67%]77%88%+0.28+0.292026-08-05 → 2026-08-30
tmax12Znearest90d26 1 QC1.28 [0.96, 1.64]1.27-0.34 [-0.81, 0.55]1.69 [1.30, 2.03]54% [33%, 67%]77%88%+0.28+0.292026-08-05 → 2026-08-30
tmax12Znearest365d26 1 QC1.28 [0.91, 1.69]1.27-0.34 [-0.83, 0.57]1.69 [1.23, 2.05]54% [30%, 68%]77%88%+0.28+0.292026-08-05 → 2026-08-30
tmax12Znearestall26 1 QC1.28 [0.98, 1.69]1.27-0.34 [-0.87, 0.61]1.69 [1.33, 2.08]54% [28%, 69%]77%88%+0.28+0.292026-08-05 → 2026-08-30
tmin00Zbilinear30d26 1 QC2.12 [1.74, 2.49]1.75-0.80 [-2.17, 0.61]2.39 [2.01, 2.72]19% [4%, 33%]46%81%-0.53-0.222026-08-05 → 2026-08-30
tmin00Zbilinear90d26 1 QC2.12 [1.70, 2.50]1.75-0.80 [-2.28, 0.88]2.39 [1.95, 2.74]19% [3%, 35%]46%81%-0.53-0.222026-08-05 → 2026-08-30
tmin00Zbilinear365d26 1 QC2.12 [1.68, 2.59]1.75-0.80 [-2.32, 1.00]2.39 [1.93, 2.76]19% [0%, 36%]46%81%-0.53-0.222026-08-05 → 2026-08-30
tmin00Zbilinearall26 1 QC2.12 [1.65, 2.51]1.75-0.80 [-2.34, 0.82]2.39 [1.95, 2.73]19% [0%, 38%]46%81%-0.53-0.222026-08-05 → 2026-08-30
tmin00Znearest30d26 1 QC1.92 [1.46, 2.32]1.77-0.36 [-1.74, 1.03]2.30 [1.77, 2.71]23% [4%, 46%]62%81%-0.38-0.232026-08-05 → 2026-08-30
tmin00Znearest90d26 1 QC1.92 [1.40, 2.34]1.77-0.36 [-1.83, 1.28]2.30 [1.65, 2.82]23% [4%, 50%]62%81%-0.38-0.232026-08-05 → 2026-08-30
tmin00Znearest365d26 1 QC1.92 [1.38, 2.39]1.77-0.36 [-1.89, 1.41]2.30 [1.56, 2.88]23% [0%, 50%]62%81%-0.38-0.232026-08-05 → 2026-08-30
tmin00Znearestall26 1 QC1.92 [1.40, 2.32]1.77-0.36 [-1.90, 1.25]2.30 [1.65, 2.76]23% [0%, 56%]62%81%-0.38-0.232026-08-05 → 2026-08-30
tmin12Zbilinear30d26 1 QC2.18 [1.81, 2.64]1.90-0.72 [-2.06, 0.66]2.52 [2.06, 3.03]15% [4%, 25%]46%77%-0.57-0.322026-08-05 → 2026-08-30
tmin12Zbilinear90d26 1 QC2.18 [1.76, 2.70]1.90-0.72 [-2.14, 0.98]2.52 [2.00, 3.13]15% [0%, 26%]46%77%-0.57-0.322026-08-05 → 2026-08-30
tmin12Zbilinear365d26 1 QC2.18 [1.75, 2.70]1.90-0.72 [-2.16, 1.11]2.52 [2.00, 3.18]15% [0%, 27%]46%77%-0.57-0.322026-08-05 → 2026-08-30
tmin12Zbilinearall26 1 QC2.18 [1.72, 2.66]1.90-0.72 [-2.20, 0.88]2.52 [2.02, 3.09]15% [0%, 28%]46%77%-0.57-0.322026-08-05 → 2026-08-30
tmin12Znearest30d26 1 QC2.01 [1.57, 2.48]1.90-0.28 [-1.64, 1.10]2.43 [1.77, 3.09]31% [14%, 48%]65%85%-0.45-0.322026-08-05 → 2026-08-30
tmin12Znearest90d26 1 QC2.01 [1.54, 2.60]1.90-0.28 [-1.72, 1.43]2.43 [1.71, 3.26]31% [12%, 50%]65%85%-0.45-0.322026-08-05 → 2026-08-30
tmin12Znearest365d26 1 QC2.01 [1.50, 2.69]1.90-0.28 [-1.74, 1.56]2.43 [1.66, 3.35]31% [10%, 50%]65%85%-0.45-0.322026-08-05 → 2026-08-30
tmin12Znearestall26 1 QC2.01 [1.54, 2.56]1.90-0.28 [-1.77, 1.33]2.43 [1.68, 3.21]31% [11%, 50%]65%85%-0.45-0.322026-08-05 → 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 KSAT, lead day 4, 00Z bilinear tmax+10+50-5-102026-08-05: +2.57 °F2026-08-06: -4.63 °F2026-08-07: -5.67 °F2026-08-08: -1.03 °F2026-08-09: -4.98 °F2026-08-10: +0.53 °F2026-08-11: -0.29 °F2026-08-12: +0.59 °F2026-08-13: -3.17 °F2026-08-14: -0.6 °F2026-08-15: -0.18 °F2026-08-16: +1.83 °F2026-08-17: +1.18 °F2026-08-18: -0.24 °F2026-08-19: -0.8 °F2026-08-20: +0.68 °F2026-08-21: -0.88 °F2026-08-22: -1.56 °F2026-08-23: -2.29 °F2026-08-24: -1.69 °F2026-08-25: -0.89 °F2026-08-26: +0.71 °F2026-08-27: -2.95 °F2026-08-28: -0.9 °F2026-08-29: +3.23 °F2026-08-30: -0.23 °F2026-08-052026-08-30°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 (26 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-0.23
2026-08-29+3.23
2026-08-28-0.90
2026-08-27-2.95
2026-08-26+0.71
2026-08-25-0.89
2026-08-24-1.69
2026-08-23-2.29
2026-08-22-1.56
2026-08-21-0.88
2026-08-20+0.68
2026-08-19-0.80
2026-08-18-0.24
2026-08-17+1.18
2026-08-16+1.83
2026-08-15-0.18
2026-08-14-0.60
2026-08-13-3.17
2026-08-12+0.59
2026-08-11-0.29
2026-08-10+0.53
2026-08-09-4.98
2026-08-08-1.03
2026-08-07-5.67
2026-08-06-4.63
2026-08-05+2.57

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KSAT, lead day 4-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 0 days-6 to -5 °F: 1 day-5 to -4 °F: 2 days-4 to -3 °F: 1 day-3 to -2 °F: 2 days-2 to -1 °F: 3 days-1 to 0 °F: 9 days0 to 1 °F: 4 days1 to 2 °F: 2 days2 to 3 °F: 1 day3 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| 0.96 · P90 |e| 3.93 °F-100+10 °Fn = 26 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
-8.00-7.000
-7.00-6.000
-6.00-5.001
-5.00-4.002
-4.00-3.001
-3.00-2.002
-2.00-1.003
-1.00+0.009
+0.00+1.004
+1.00+2.002
+2.00+3.001
+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
2026-08261.70 -0.83

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-05 → 2026-08-30 26
NCEP GFS2026-08-05 → 2026-08-30 26
NCEP GFS2026-08-05 → 2026-08-30 26
NCEP GFS2026-08-05 → 2026-08-30 26

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 26 -1.12 [-1.90, 0.23] no
GraphCast (IFS init) 25 -3.76 [-5.61, -0.65] yes
ECMWF IFS HRES 20 -1.21 [-1.85, 0.17] no
Persistence (baseline) 26 -0.07 [-1.01, 1.63] no

Cite this page

ShortCastCheck, KSAT gfs lead 4, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSAT/model/gfs/lead/4/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAT (San Antonio Intl), model gfs, lead day 4. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KSAT/model/gfs/lead/4/

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