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

San Antonio Intl · GraphCast (IFS init) · lead day 6

KSAT · graphcast_ifs · lead 6

Target day = initialization date + 6 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
tmax00Zbilinear30d24 1 QC5.40 [3.45, 6.98]2.08-5.40 [-6.98, -3.45]5.91 [3.64, 7.37]0% [0%, 0%]0%12%-1.65-0.022026-08-07 → 2026-08-30
tmax00Zbilinear90d24 1 QC5.40 [3.09, 7.17]2.08-5.40 [-7.17, -3.09]5.91 [3.14, 7.50]0% [0%, 0%]0%12%-1.65-0.022026-08-07 → 2026-08-30
tmax00Zbilinear365d30 1 QC5.87 [4.21, 7.67]2.51-5.87 [-7.67, -4.21]6.70 [4.70, 8.60]0% [0%, 0%]0%13%-0.53+0.392026-01-07 → 2026-08-30
tmax00Zbilinearall30 1 QC5.87 [4.13, 7.67]2.51-5.87 [-7.67, -4.13]6.70 [4.73, 8.54]0% [0%, 0%]0%13%-0.53+0.392026-01-07 → 2026-08-30
tmax00Znearest30d24 1 QC5.08 [3.11, 6.69]2.10-5.08 [-6.69, -3.11]5.63 [3.32, 7.10]0% [0%, 0%]0%29%-1.49-0.032026-08-07 → 2026-08-30
tmax00Znearest90d24 1 QC5.08 [2.73, 6.87]2.10-5.08 [-6.87, -2.73]5.63 [2.80, 7.22]0% [0%, 0%]0%29%-1.49-0.032026-08-07 → 2026-08-30
tmax00Znearest365d30 1 QC5.56 [3.87, 7.40]2.54-5.56 [-7.40, -3.87]6.46 [4.40, 8.43]0% [0%, 0%]0%27%-0.45+0.382026-01-07 → 2026-08-30
tmax00Znearestall30 1 QC5.56 [3.81, 7.40]2.54-5.56 [-7.40, -3.81]6.46 [4.42, 8.29]0% [0%, 0%]0%27%-0.45+0.382026-01-07 → 2026-08-30
tmax12Zbilinear30d24 1 QC5.69 [3.89, 7.17]1.82-5.69 [-7.17, -3.89]6.14 [4.02, 7.56]0% [0%, 0%]0%8%-1.79+0.112026-08-07 → 2026-08-30
tmax12Zbilinear90d24 1 QC5.69 [3.60, 7.34]1.82-5.69 [-7.34, -3.60]6.14 [3.68, 7.71]0% [0%, 0%]0%8%-1.79+0.112026-08-07 → 2026-08-30
tmax12Zbilinear365d29 1 QC5.50 [3.74, 7.09]2.04-5.50 [-7.09, -3.74]6.09 [4.12, 7.52]3% [0%, 13%]3%14%-0.70+0.392026-01-07 → 2026-08-30
tmax12Zbilinearall29 1 QC5.50 [3.76, 7.05]2.04-5.50 [-7.05, -3.76]6.09 [4.12, 7.55]3% [0%, 15%]3%14%-0.70+0.392026-01-07 → 2026-08-30
tmax12Znearest30d24 1 QC5.37 [3.51, 6.90]1.87-5.37 [-6.90, -3.51]5.87 [3.67, 7.34]0% [0%, 0%]4%8%-1.63+0.092026-08-07 → 2026-08-30
tmax12Znearest90d24 1 QC5.37 [3.19, 7.07]1.87-5.37 [-7.07, -3.19]5.87 [3.29, 7.47]0% [0%, 0%]4%8%-1.63+0.092026-08-07 → 2026-08-30
tmax12Znearest365d29 1 QC5.21 [3.43, 6.81]2.08-5.21 [-6.81, -3.43]5.85 [3.82, 7.32]3% [0%, 13%]10%14%-0.61+0.372026-01-07 → 2026-08-30
tmax12Znearestall29 1 QC5.21 [3.44, 6.78]2.08-5.21 [-6.78, -3.44]5.85 [3.80, 7.32]3% [0%, 15%]10%14%-0.61+0.372026-01-07 → 2026-08-30
tmin00Zbilinear30d24 1 QC1.36 [0.72, 2.19]1.26+1.11 [0.33, 1.97]2.11 [0.93, 3.17]67% [50%, 85%]71%92%+0.12+0.202026-08-07 → 2026-08-30
tmin00Zbilinear90d24 1 QC1.36 [0.68, 2.46]1.26+1.11 [0.31, 2.20]2.11 [0.89, 3.47]67% [46%, 88%]71%92%+0.12+0.202026-08-07 → 2026-08-30
tmin00Zbilinear365d30 1 QC1.52 [0.82, 2.31]1.31+1.32 [0.52, 2.16]2.20 [1.11, 3.21]57% [31%, 80%]67%90%+0.51+0.592026-01-07 → 2026-08-30
tmin00Zbilinearall30 1 QC1.52 [0.82, 2.31]1.31+1.32 [0.50, 2.16]2.20 [1.09, 3.13]57% [29%, 79%]67%90%+0.51+0.592026-01-07 → 2026-08-30
tmin00Znearest30d24 1 QC1.51 [0.84, 2.34]1.26+1.34 [0.57, 2.19]2.24 [1.05, 3.33]58% [40%, 76%]71%88%+0.02+0.202026-08-07 → 2026-08-30
tmin00Znearest90d24 1 QC1.51 [0.82, 2.59]1.26+1.34 [0.54, 2.43]2.24 [1.02, 3.63]58% [38%, 78%]71%88%+0.02+0.202026-08-07 → 2026-08-30
tmin00Znearest365d30 1 QC1.65 [0.98, 2.46]1.29+1.52 [0.74, 2.34]2.32 [1.23, 3.35]50% [28%, 71%]67%87%+0.47+0.592026-01-07 → 2026-08-30
tmin00Znearestall30 1 QC1.65 [0.97, 2.39]1.29+1.52 [0.71, 2.32]2.32 [1.23, 3.28]50% [26%, 71%]67%87%+0.47+0.592026-01-07 → 2026-08-30
tmin12Zbilinear30d24 1 QC1.23 [0.72, 1.84]1.21+0.63 [-0.08, 1.34]1.78 [0.91, 2.59]58% [38%, 77%]83%96%+0.20+0.232026-08-07 → 2026-08-30
tmin12Zbilinear90d24 1 QC1.23 [0.64, 2.04]1.21+0.63 [-0.11, 1.50]1.78 [0.83, 2.78]58% [33%, 80%]83%96%+0.20+0.232026-08-07 → 2026-08-30
tmin12Zbilinear365d29 1 QC1.68 [0.80, 2.94]1.64+1.18 [0.11, 2.64]2.28 [1.01, 3.38]48% [16%, 73%]69%79%+0.38+0.412026-01-07 → 2026-08-30
tmin12Zbilinearall29 1 QC1.68 [0.83, 3.10]1.64+1.18 [0.11, 2.89]2.28 [1.07, 3.39]48% [14%, 72%]69%79%+0.38+0.412026-01-07 → 2026-08-30
tmin12Znearest30d24 1 QC1.30 [0.79, 1.91]1.21+0.85 [0.14, 1.56]1.87 [0.97, 2.71]58% [45%, 75%]79%92%+0.15+0.232026-08-07 → 2026-08-30
tmin12Znearest90d24 1 QC1.30 [0.73, 2.11]1.21+0.85 [0.11, 1.70]1.87 [0.90, 2.91]58% [43%, 79%]79%92%+0.15+0.232026-08-07 → 2026-08-30
tmin12Znearest365d29 1 QC1.76 [0.85, 3.02]1.61+1.38 [0.33, 2.78]2.37 [1.11, 3.47]48% [21%, 70%]66%76%+0.36+0.422026-01-07 → 2026-08-30
tmin12Znearestall29 1 QC1.76 [0.87, 3.23]1.61+1.38 [0.33, 3.04]2.37 [1.11, 3.53]48% [19%, 69%]66%76%+0.36+0.422026-01-07 → 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 6, 00Z bilinear tmax+20+100-10-202026-08-07: -2.45 °F2026-08-08: -2.72 °F2026-08-09: -3.3 °F2026-08-10: -3.19 °F2026-08-11: -2.46 °F2026-08-12: -3.71 °F2026-08-13: -6.68 °F2026-08-14: -3.35 °F2026-08-15: -7.98 °F2026-08-16: -5.35 °F2026-08-17: -6.03 °F2026-08-18: -7.27 °F2026-08-19: -5.85 °F2026-08-20: -7.17 °F2026-08-21: -7.3 °F2026-08-22: -10.18 °F2026-08-23: -10.67 °F2026-08-24: -8.87 °F2026-08-25: -6.33 °F2026-08-26: -3.18 °F2026-08-27: -4.33 °F2026-08-28: -4.42 °F2026-08-29: -3.82 °F2026-08-30: -3.02 °F2026-08-072026-08-30°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 (24 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-3.02
2026-08-29-3.82
2026-08-28-4.42
2026-08-27-4.33
2026-08-26-3.18
2026-08-25-6.33
2026-08-24-8.87
2026-08-23-10.67
2026-08-22-10.18
2026-08-21-7.30
2026-08-20-7.17
2026-08-19-5.85
2026-08-18-7.27
2026-08-17-6.03
2026-08-16-5.35
2026-08-15-7.98
2026-08-14-3.35
2026-08-13-6.68
2026-08-12-3.71
2026-08-11-2.46
2026-08-10-3.19
2026-08-09-3.30
2026-08-08-2.72
2026-08-07-2.45

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAT, lead day 6-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 1 day-14 to -12 °F: 1 day-12 to -10 °F: 2 days-10 to -8 °F: 1 day-8 to -6 °F: 8 days-6 to -4 °F: 5 days-4 to -2 °F: 12 days-2 to 0 °F: 0 days0 to 2 °F: 0 days2 to 4 °F: 0 days4 to 6 °F: 0 days6 to 8 °F: 0 days8 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| 4.88 · P90 |e| 10.23 °F-200+20 °Fn = 30 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
-14.00-12.001
-12.00-10.002
-10.00-8.001
-8.00-6.008
-6.00-4.005
-4.00-2.0012
-2.00+0.000
+0.00+2.000
+2.00+4.000
+4.00+6.000
+6.00+8.000
+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
2026-08245.40 -5.40
2026-0167.74 -7.74

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-07 → 2026-08-30 30
GraphCast (IFS init)2026-01-07 → 2026-08-30 30
GraphCast (IFS init)2026-01-07 → 2026-08-30 29
GraphCast (IFS init)2026-01-07 → 2026-08-30 29

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 24 +2.76 [0.12, 4.11] yes
NCEP GFS 24 +3.78 [1.17, 5.79] yes
ECMWF IFS HRES 19 +3.08 [1.35, 4.41] yes
Persistence (baseline) 24 +3.36 [0.87, 5.03] yes

Cite this page

ShortCastCheck, KSAT graphcast_ifs lead 6, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSAT/model/graphcast_ifs/lead/6/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAT (San Antonio Intl), model graphcast_ifs, lead day 6. 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/6/

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