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

San Antonio Intl · GraphCast (IFS init) · lead day 0

KSAT · graphcast_ifs · lead 0

Target day = initialization date + 0 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, GRAP_v100, starting 2026-01-01 — 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
tmax00Zbilinear30d28 1 QC5.46 [5.03, 5.88]1.02-5.46 [-5.88, -5.03]5.59 [5.14, 6.00]0% [0%, 0%]0%4%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d28 1 QC5.46 [4.93, 5.97]1.02-5.46 [-5.97, -4.93]5.59 [5.05, 6.09]0% [0%, 0%]0%4%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d34 1 QC5.83 [5.19, 6.74]1.32-5.83 [-6.74, -5.19]6.04 [5.30, 7.01]0% [0%, 0%]0%3%——2026-01-01 → 2026-08-30
tmax00Zbilinearall34 1 QC5.83 [5.16, 6.56]1.32-5.83 [-6.56, -5.16]6.04 [5.29, 6.85]0% [0%, 0%]0%3%——2026-01-01 → 2026-08-30
tmax00Znearest30d28 1 QC4.96 [4.55, 5.36]1.04-4.96 [-5.36, -4.55]5.12 [4.69, 5.52]0% [0%, 0%]0%4%——2026-08-01 → 2026-08-30
tmax00Znearest90d28 1 QC4.96 [4.47, 5.46]1.04-4.96 [-5.46, -4.47]5.12 [4.59, 5.61]0% [0%, 0%]0%4%——2026-08-01 → 2026-08-30
tmax00Znearest365d34 1 QC5.38 [4.70, 6.42]1.42-5.38 [-6.42, -4.70]5.65 [4.85, 6.75]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmax00Znearestall34 1 QC5.38 [4.68, 6.23]1.42-5.38 [-6.23, -4.68]5.65 [4.84, 6.60]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmin00Zbilinear30d28 1 QC1.25 [0.79, 1.76]1.22+0.46 [-0.24, 1.36]1.58 [0.96, 2.13]50% [28%, 73%]79%93%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d28 1 QC1.25 [0.81, 1.94]1.22+0.46 [-0.33, 1.45]1.58 [0.97, 2.24]50% [20%, 72%]79%93%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d34 1 QC1.73 [0.99, 2.96]1.67+0.93 [-0.13, 2.18]2.53 [1.17, 3.97]41% [10%, 67%]71%85%——2026-01-01 → 2026-08-30
tmin00Zbilinearall34 1 QC1.73 [0.95, 2.79]1.67+0.93 [-0.12, 2.15]2.53 [1.15, 3.83]41% [12%, 67%]71%85%——2026-01-01 → 2026-08-30
tmin00Znearest30d28 1 QC1.38 [0.81, 2.07]1.23+0.84 [0.13, 1.76]1.75 [1.00, 2.43]46% [19%, 77%]79%93%——2026-08-01 → 2026-08-30
tmin00Znearest90d28 1 QC1.38 [0.82, 2.17]1.23+0.84 [0.06, 1.86]1.75 [1.02, 2.48]46% [13%, 72%]79%93%——2026-08-01 → 2026-08-30
tmin00Znearest365d34 1 QC1.89 [1.00, 3.21]1.67+1.27 [0.23, 2.43]2.68 [1.22, 4.16]38% [6%, 66%]68%85%——2026-01-01 → 2026-08-30
tmin00Znearestall34 1 QC1.89 [1.00, 3.06]1.67+1.27 [0.24, 2.43]2.68 [1.27, 3.99]38% [6%, 66%]68%85%——2026-01-01 → 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 GraphCast (IFS init) at KSAT, lead day 0, 00Z bilinear tmax+10+50-5-102026-08-01: -4.76 °F2026-08-02: -4.23 °F2026-08-03: -3.83 °F2026-08-04: -4.45 °F2026-08-05: -5.15 °F2026-08-06: -5.14 °F2026-08-07: -6.98 °F2026-08-08: -2.78 °F2026-08-09: -5.99 °F2026-08-10: -6.07 °F2026-08-11: -6.75 °F2026-08-12: -5.91 °F2026-08-13: -7.3 °F2026-08-14: -6.43 °F2026-08-15: -6.36 °F2026-08-16: -3.84 °F2026-08-17: -4.41 °F2026-08-18: -4.47 °F2026-08-19: -5.62 °F2026-08-20: -6.83 °F2026-08-21: -5.14 °F2026-08-22: -5.97 °F2026-08-23: -5.33 °F2026-08-24: -4.26 °F2026-08-25: -5.14 °F2026-08-28: -8.06 °F2026-08-29: -6.91 °F2026-08-30: -4.63 °F2026-08-012026-08-30°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 (30 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-4.63
2026-08-29-6.91
2026-08-28-8.06
2026-08-27—
2026-08-26—
2026-08-25-5.14
2026-08-24-4.26
2026-08-23-5.33
2026-08-22-5.97
2026-08-21-5.14
2026-08-20-6.83
2026-08-19-5.62
2026-08-18-4.47
2026-08-17-4.41
2026-08-16-3.84
2026-08-15-6.36
2026-08-14-6.43
2026-08-13-7.30
2026-08-12-5.91
2026-08-11-6.75
2026-08-10-6.07
2026-08-09-5.99
2026-08-08-2.78
2026-08-07-6.98
2026-08-06-5.14
2026-08-05-5.15
2026-08-04-4.45
2026-08-03-3.83
2026-08-02-4.23
2026-08-01-4.76

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAT, lead day 0-10 to -9 °F: 1 day-9 to -8 °F: 3 days-8 to -7 °F: 3 days-7 to -6 °F: 7 days-6 to -5 °F: 9 days-5 to -4 °F: 7 days-4 to -3 °F: 3 days-3 to -2 °F: 1 day-2 to -1 °F: 0 days-1 to 0 °F: 0 days0 to 1 °F: 0 days1 to 2 °F: 0 days2 to 3 °F: 0 days3 to 4 °F: 0 days4 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| 5.77 · P90 |e| 7.95 °F-100+10 °Fn = 34 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
-10.00-9.001
-9.00-8.003
-8.00-7.003
-7.00-6.007
-6.00-5.009
-5.00-4.007
-4.00-3.003
-3.00-2.001
-2.00-1.000
-1.00+0.000
+0.00+1.000
+1.00+2.000
+2.00+3.000
+3.00+4.000
+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
2026-08285.46 -5.46
2026-0167.55 -7.55

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-01 → 2026-08-30 34
GraphCast (IFS init)2026-01-01 → 2026-08-30 34

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 28 +2.33 [1.37, 3.04] yes
Aurora (GFS init) 2 -1.56 [-2.52, -0.59] yes
Aurora (IFS init) 3 +0.25 [0.05, 0.66] yes
FourCastNet v2 (GFS init) 2 +1.43 [0.97, 1.89] yes
FourCastNet v2 (IFS init) 3 +2.32 [1.89, 2.54] yes
NCEP GFS 28 +3.33 [2.73, 3.78] yes
GraphCast (GFS init) 2 -0.90 [-1.31, -0.49] yes
ECMWF IFS HRES 22 +2.30 [1.23, 2.85] yes
Pangu-Weather (GFS init) 2 +2.74 [1.98, 3.50] yes
Pangu-Weather (IFS init) 3 +3.81 [2.31, 5.08] yes

Cite this page

ShortCastCheck, KSAT graphcast_ifs lead 0, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSAT/model/graphcast_ifs/lead/0/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAT (San Antonio Intl), model graphcast_ifs, lead day 0. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KSAT/model/graphcast_ifs/lead/0/

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

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