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

San Antonio Intl · GraphCast (IFS init) · lead day 9

KSAT · graphcast_ifs · 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, 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
tmax00Zbilinear30d21 1 QC6.16 [4.88, 7.10]1.93-6.16 [-7.10, -4.88]6.60 [5.54, 7.42]0% [0%, 0%]5%19%-1.88-0.132026-08-10 → 2026-08-30
tmax00Zbilinear90d21 1 QC6.16 [4.69, 7.22]1.93-6.16 [-7.22, -4.69]6.60 [5.44, 7.51]0% [0%, 0%]5%19%-1.88-0.132026-08-10 → 2026-08-30
tmax00Zbilinear365d27 1 QC6.20 [4.89, 7.34]3.44-4.97 [-6.83, -1.86]6.80 [5.51, 7.92]0% [0%, 0%]7%19%-0.34+0.372026-01-10 → 2026-08-30
tmax00Zbilinearall27 1 QC6.20 [4.90, 7.34]3.44-4.97 [-6.77, -1.89]6.80 [5.48, 7.95]0% [0%, 0%]7%19%-0.34+0.372026-01-10 → 2026-08-30
tmax00Znearest30d21 1 QC5.87 [4.56, 6.83]1.96-5.87 [-6.83, -4.56]6.34 [5.27, 7.16]0% [0%, 0%]10%19%-1.74-0.142026-08-10 → 2026-08-30
tmax00Znearest90d21 1 QC5.87 [4.37, 6.94]1.96-5.87 [-6.94, -4.37]6.34 [5.18, 7.27]0% [0%, 0%]10%19%-1.74-0.142026-08-10 → 2026-08-30
tmax00Znearest365d27 1 QC5.98 [4.70, 7.12]3.43-4.73 [-6.56, -1.53]6.60 [5.30, 7.84]0% [0%, 0%]7%19%-0.29+0.372026-01-10 → 2026-08-30
tmax00Znearestall27 1 QC5.98 [4.65, 7.18]3.43-4.73 [-6.51, -1.75]6.60 [5.27, 7.74]0% [0%, 0%]7%19%-0.29+0.372026-01-10 → 2026-08-30
tmax12Zbilinear30d21 1 QC6.16 [4.57, 7.36]1.80-6.16 [-7.36, -4.57]6.50 [4.86, 7.51]0% [0%, 0%]0%10%-1.87-0.052026-08-10 → 2026-08-30
tmax12Zbilinear90d21 1 QC6.16 [3.97, 7.50]1.80-6.16 [-7.50, -3.97]6.50 [3.97, 7.62]0% [0%, 0%]0%10%-1.87-0.052026-08-10 → 2026-08-30
tmax12Zbilinear365d26 1 QC5.65 [3.64, 7.06]2.70-5.20 [-7.05, -2.07]6.17 [4.22, 7.29]0% [0%, 0%]12%19%-0.35+0.442026-01-10 → 2026-08-30
tmax12Zbilinearall26 1 QC5.65 [3.59, 7.03]2.70-5.20 [-6.99, -1.88]6.17 [4.33, 7.29]0% [0%, 0%]12%19%-0.35+0.442026-01-10 → 2026-08-30
tmax12Znearest30d21 1 QC5.86 [4.23, 7.09]1.84-5.86 [-7.09, -4.23]6.23 [4.56, 7.25]0% [0%, 0%]0%10%-1.73-0.072026-08-10 → 2026-08-30
tmax12Znearest90d21 1 QC5.86 [3.61, 7.22]1.84-5.86 [-7.22, -3.61]6.23 [3.64, 7.35]0% [0%, 0%]0%10%-1.73-0.072026-08-10 → 2026-08-30
tmax12Znearest365d26 1 QC5.39 [3.44, 6.79]2.71-4.93 [-6.77, -1.84]5.93 [4.05, 7.03]0% [0%, 0%]12%19%-0.29+0.442026-01-10 → 2026-08-30
tmax12Znearestall26 1 QC5.39 [3.45, 6.75]2.71-4.93 [-6.71, -1.65]5.93 [4.19, 7.04]0% [0%, 0%]12%19%-0.29+0.442026-01-10 → 2026-08-30
tmin00Zbilinear30d21 1 QC1.61 [0.82, 2.59]1.54+1.07 [0.23, 2.20]2.36 [1.05, 3.54]48% [25%, 69%]67%86%+0.11+0.132026-08-10 → 2026-08-30
tmin00Zbilinear90d21 1 QC1.61 [0.81, 2.82]1.54+1.07 [0.19, 2.55]2.36 [1.04, 3.87]48% [22%, 71%]67%86%+0.11+0.132026-08-10 → 2026-08-30
tmin00Zbilinear365d27 1 QC3.23 [1.12, 7.30]3.38+2.17 [0.43, 5.40]5.77 [1.49, 10.25]37% [7%, 60%]52%67%+0.15+0.182026-01-10 → 2026-08-30
tmin00Zbilinearall27 1 QC3.23 [1.19, 7.66]3.38+2.17 [0.47, 5.49]5.77 [1.50, 10.64]37% [5%, 62%]52%67%+0.15+0.182026-01-10 → 2026-08-30
tmin00Znearest30d21 1 QC1.76 [0.99, 2.74]1.55+1.29 [0.44, 2.43]2.47 [1.14, 3.67]43% [21%, 62%]71%81%+0.03+0.122026-08-10 → 2026-08-30
tmin00Znearest90d21 1 QC1.76 [0.97, 3.00]1.55+1.29 [0.40, 2.77]2.47 [1.14, 4.02]43% [17%, 64%]71%81%+0.03+0.122026-08-10 → 2026-08-30
tmin00Znearest365d27 1 QC3.34 [1.27, 7.37]3.33+2.32 [0.60, 5.41]5.81 [1.60, 10.32]33% [3%, 55%]56%63%+0.12+0.192026-01-10 → 2026-08-30
tmin00Znearestall27 1 QC3.34 [1.34, 7.69]3.33+2.32 [0.68, 5.57]5.81 [1.63, 10.67]33% [0%, 56%]56%63%+0.12+0.192026-01-10 → 2026-08-30
tmin12Zbilinear30d21 1 QC1.32 [0.77, 2.09]1.35+0.80 [-0.00, 1.71]2.11 [0.91, 3.27]62% [46%, 82%]86%90%+0.27+0.242026-08-10 → 2026-08-30
tmin12Zbilinear90d21 1 QC1.32 [0.67, 2.32]1.35+0.80 [-0.04, 1.93]2.11 [0.76, 3.59]62% [45%, 90%]86%90%+0.27+0.242026-08-10 → 2026-08-30
tmin12Zbilinear365d26 1 QC2.17 [0.89, 4.32]2.17+0.82 [-0.24, 2.10]3.21 [1.04, 5.02]50% [20%, 75%]69%73%+0.31+0.362026-01-10 → 2026-08-30
tmin12Zbilinearall26 1 QC2.17 [0.91, 4.80]2.17+0.82 [-0.13, 1.93]3.21 [1.11, 5.27]50% [17%, 73%]69%73%+0.31+0.362026-01-10 → 2026-08-30
tmin12Znearest30d21 1 QC1.40 [0.83, 2.16]1.35+1.01 [0.21, 1.91]2.19 [0.94, 3.37]62% [46%, 82%]81%90%+0.23+0.242026-08-10 → 2026-08-30
tmin12Znearest90d21 1 QC1.40 [0.69, 2.37]1.35+1.01 [0.18, 2.15]2.19 [0.74, 3.70]62% [45%, 90%]81%90%+0.23+0.242026-08-10 → 2026-08-30
tmin12Znearest365d26 1 QC2.24 [0.95, 4.37]2.15+0.98 [-0.11, 2.29]3.27 [1.10, 5.08]50% [20%, 75%]65%73%+0.29+0.372026-01-10 → 2026-08-30
tmin12Znearestall26 1 QC2.24 [0.97, 4.81]2.15+0.98 [-0.00, 2.09]3.27 [1.19, 5.33]50% [17%, 73%]65%73%+0.29+0.372026-01-10 → 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 GraphCast (IFS init) at KSAT, lead day 9, 00Z bilinear tmax+20+100-10-202026-08-10: -1.76 °F2026-08-11: -10.8 °F2026-08-12: -4.07 °F2026-08-13: -4.5 °F2026-08-14: -2.79 °F2026-08-15: -6.89 °F2026-08-16: -5.42 °F2026-08-17: -6.11 °F2026-08-18: -5.64 °F2026-08-19: -6.94 °F2026-08-20: -7.76 °F2026-08-21: -6.42 °F2026-08-22: -7.56 °F2026-08-23: -8 °F2026-08-24: -9.34 °F2026-08-25: -8.11 °F2026-08-26: -7.14 °F2026-08-27: -7.81 °F2026-08-28: -2.87 °F2026-08-29: -7.49 °F2026-08-30: -2.01 °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
2026-08-30-2.01
2026-08-29-7.49
2026-08-28-2.87
2026-08-27-7.81
2026-08-26-7.14
2026-08-25-8.11
2026-08-24-9.34
2026-08-23-8.00
2026-08-22-7.56
2026-08-21-6.42
2026-08-20-7.76
2026-08-19-6.94
2026-08-18-5.64
2026-08-17-6.11
2026-08-16-5.42
2026-08-15-6.89
2026-08-14-2.79
2026-08-13-4.50
2026-08-12-4.07
2026-08-11-10.80
2026-08-10-1.76

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAT, 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: 1 day-10 to -8 °F: 3 days-8 to -6 °F: 9 days-6 to -4 °F: 5 days-4 to -2 °F: 3 days-2 to 0 °F: 2 days0 to 2 °F: 0 days2 to 4 °F: 1 day4 to 6 °F: 1 day6 to 8 °F: 1 day8 to 10 °F: 0 days10 to 12 °F: 0 days12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 6.42 · P90 |e| 8.6 °F-200+20 °Fn = 27 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
-12.00-10.001
-10.00-8.003
-8.00-6.009
-6.00-4.005
-4.00-2.003
-2.00+0.002
+0.00+2.000
+2.00+4.001
+4.00+6.001
+6.00+8.001
+8.00+10.000
+10.00+12.000
+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
2026-08216.16 -6.16
2026-0166.35 -0.79

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-10 → 2026-08-30 27
GraphCast (IFS init)2026-01-10 → 2026-08-30 27
GraphCast (IFS init)2026-01-10 → 2026-08-30 26
GraphCast (IFS init)2026-01-10 → 2026-08-30 26

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 21 +3.02 [2.35, 3.48] yes
NCEP GFS 21 +3.75 [1.80, 4.63] yes
ECMWF IFS HRES 16 +3.27 [-0.29, 3.99] no
Persistence (baseline) 21 +4.02 [2.03, 5.05] yes

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAT (San Antonio Intl), model graphcast_ifs, 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/KSAT/model/graphcast_ifs/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