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

San Antonio Intl · GraphCast (IFS init) · lead day 8

KSAT · graphcast_ifs · lead 8

Target day = initialization date + 8 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
tmax00Zbilinear30d22 1 QC5.89 [4.29, 7.21]2.01-5.89 [-7.21, -4.29]6.36 [4.85, 7.50]0% [0%, 0%]5%14%-1.70-0.022026-08-09 → 2026-08-30
tmax00Zbilinear90d22 1 QC5.89 [4.00, 7.32]2.01-5.89 [-7.32, -4.00]6.36 [4.53, 7.59]0% [0%, 0%]5%14%-1.70-0.022026-08-09 → 2026-08-30
tmax00Zbilinear365d28 1 QC5.12 [2.85, 6.84]2.56-4.80 [-6.76, -2.07]5.77 [3.35, 7.18]4% [0%, 13%]11%29%-0.17+0.482026-01-09 → 2026-08-30
tmax00Zbilinearall28 1 QC5.12 [2.74, 6.75]2.56-4.80 [-6.74, -1.68]5.77 [3.14, 7.18]4% [0%, 14%]11%29%-0.17+0.482026-01-09 → 2026-08-30
tmax00Znearest30d22 1 QC5.58 [3.96, 6.91]2.05-5.58 [-6.91, -3.96]6.10 [4.59, 7.22]5% [0%, 18%]9%23%-1.56-0.042026-08-09 → 2026-08-30
tmax00Znearest90d22 1 QC5.58 [3.65, 7.01]2.05-5.58 [-7.01, -3.65]6.10 [4.26, 7.32]5% [0%, 22%]9%23%-1.56-0.042026-08-09 → 2026-08-30
tmax00Znearest365d28 1 QC4.86 [2.67, 6.56]2.54-4.54 [-6.48, -1.83]5.54 [3.22, 6.92]7% [0%, 20%]14%36%-0.12+0.482026-01-09 → 2026-08-30
tmax00Znearestall28 1 QC4.86 [2.55, 6.48]2.54-4.54 [-6.45, -1.51]5.54 [3.01, 6.91]7% [0%, 21%]14%36%-0.12+0.482026-01-09 → 2026-08-30
tmax12Zbilinear30d22 1 QC6.14 [4.49, 7.42]1.72-6.14 [-7.42, -4.49]6.49 [4.68, 7.69]0% [0%, 0%]0%5%-1.81+0.122026-08-09 → 2026-08-30
tmax12Zbilinear90d22 1 QC6.14 [4.14, 7.57]1.72-6.14 [-7.57, -4.14]6.49 [4.20, 7.76]0% [0%, 0%]0%5%-1.81+0.122026-08-09 → 2026-08-30
tmax12Zbilinear365d27 1 QC5.95 [4.45, 7.14]1.98-5.84 [-7.11, -4.18]6.37 [4.73, 7.46]0% [0%, 0%]4%11%-0.43+0.582026-01-09 → 2026-08-30
tmax12Zbilinearall27 1 QC5.95 [4.44, 7.21]1.98-5.84 [-7.17, -4.11]6.37 [4.73, 7.54]0% [0%, 0%]4%11%-0.43+0.582026-01-09 → 2026-08-30
tmax12Znearest30d22 1 QC5.85 [4.16, 7.15]1.74-5.85 [-7.15, -4.16]6.22 [4.38, 7.44]0% [0%, 0%]0%9%-1.68+0.112026-08-09 → 2026-08-30
tmax12Znearest90d22 1 QC5.85 [3.80, 7.29]1.74-5.85 [-7.29, -3.80]6.22 [3.86, 7.52]0% [0%, 0%]0%9%-1.68+0.112026-08-09 → 2026-08-30
tmax12Znearest365d27 1 QC5.68 [4.18, 6.88]1.98-5.57 [-6.84, -3.93]6.12 [4.45, 7.21]0% [0%, 0%]4%15%-0.37+0.582026-01-09 → 2026-08-30
tmax12Znearestall27 1 QC5.68 [4.20, 6.96]1.98-5.57 [-6.91, -3.83]6.12 [4.50, 7.29]0% [0%, 0%]4%15%-0.37+0.582026-01-09 → 2026-08-30
tmin00Zbilinear30d22 1 QC1.71 [0.87, 2.90]1.68+1.14 [0.15, 2.10]2.55 [1.03, 3.92]55% [29%, 79%]73%82%+0.03+0.082026-08-09 → 2026-08-30
tmin00Zbilinear90d22 1 QC1.71 [0.77, 3.23]1.68+1.14 [0.03, 2.32]2.55 [0.90, 4.31]55% [27%, 81%]73%82%+0.03+0.082026-08-09 → 2026-08-30
tmin00Zbilinear365d28 1 QC2.16 [1.06, 3.63]2.04+1.06 [-0.04, 2.21]2.96 [1.32, 4.30]43% [10%, 71%]61%71%+0.47+0.512026-01-09 → 2026-08-30
tmin00Zbilinearall28 1 QC2.16 [1.10, 3.70]2.04+1.06 [-0.08, 2.12]2.96 [1.46, 4.28]43% [0%, 70%]61%71%+0.47+0.512026-01-09 → 2026-08-30
tmin00Znearest30d22 1 QC1.81 [0.92, 3.01]1.69+1.36 [0.38, 2.32]2.67 [1.08, 4.06]41% [21%, 57%]64%82%-0.02+0.082026-08-09 → 2026-08-30
tmin00Znearest90d22 1 QC1.81 [0.86, 3.33]1.69+1.36 [0.26, 2.54]2.67 [0.99, 4.44]41% [15%, 57%]64%82%-0.02+0.082026-08-09 → 2026-08-30
tmin00Znearest365d28 1 QC2.25 [1.14, 3.71]2.03+1.22 [0.08, 2.37]3.07 [1.44, 4.41]32% [0%, 52%]50%71%+0.45+0.512026-01-09 → 2026-08-30
tmin00Znearestall28 1 QC2.25 [1.20, 3.76]2.03+1.22 [0.03, 2.31]3.07 [1.58, 4.39]32% [0%, 50%]50%71%+0.45+0.512026-01-09 → 2026-08-30
tmin12Zbilinear30d22 1 QC1.46 [0.60, 2.46]1.54+0.96 [0.08, 1.81]2.20 [0.83, 3.27]50% [23%, 79%]73%82%+0.17+0.162026-08-09 → 2026-08-30
tmin12Zbilinear90d22 1 QC1.46 [0.49, 2.68]1.54+0.96 [0.02, 1.96]2.20 [0.69, 3.55]50% [20%, 86%]73%82%+0.17+0.162026-08-09 → 2026-08-30
tmin12Zbilinear365d27 1 QC2.06 [0.72, 3.71]2.06+0.81 [-0.39, 1.82]3.12 [1.05, 4.81]41% [10%, 71%]63%74%+0.44+0.452026-01-09 → 2026-08-30
tmin12Zbilinearall27 1 QC2.06 [0.79, 4.07]2.06+0.81 [-0.38, 1.82]3.12 [1.12, 5.07]41% [0%, 70%]63%74%+0.44+0.452026-01-09 → 2026-08-30
tmin12Znearest30d22 1 QC1.57 [0.69, 2.56]1.53+1.17 [0.30, 2.03]2.30 [0.86, 3.40]50% [30%, 69%]73%82%+0.11+0.172026-08-09 → 2026-08-30
tmin12Znearest90d22 1 QC1.57 [0.59, 2.80]1.53+1.17 [0.25, 2.18]2.30 [0.73, 3.68]50% [27%, 73%]73%82%+0.11+0.172026-08-09 → 2026-08-30
tmin12Znearest365d27 1 QC2.17 [0.83, 3.83]2.07+1.00 [-0.20, 2.02]3.21 [1.14, 4.94]41% [12%, 64%]63%74%+0.41+0.452026-01-09 → 2026-08-30
tmin12Znearestall27 1 QC2.17 [0.88, 4.14]2.07+1.00 [-0.19, 2.04]3.21 [1.19, 5.18]41% [0%, 62%]63%74%+0.41+0.452026-01-09 → 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 8, 00Z bilinear tmax+20+100-10-202026-08-09: -1.3 °F2026-08-10: -8.36 °F2026-08-11: -2.61 °F2026-08-12: -3.19 °F2026-08-13: -4.88 °F2026-08-14: -3.28 °F2026-08-15: -8.12 °F2026-08-16: -6.09 °F2026-08-17: -5.19 °F2026-08-18: -6.66 °F2026-08-19: -8.43 °F2026-08-20: -6.17 °F2026-08-21: -5.91 °F2026-08-22: -7.61 °F2026-08-23: -10.36 °F2026-08-24: -9.64 °F2026-08-25: -7.73 °F2026-08-26: -7.68 °F2026-08-27: -4.95 °F2026-08-28: -4.87 °F2026-08-29: -2.14 °F2026-08-30: -4.42 °F2026-08-092026-08-30°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 (22 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-4.42
2026-08-29-2.14
2026-08-28-4.87
2026-08-27-4.95
2026-08-26-7.68
2026-08-25-7.73
2026-08-24-9.64
2026-08-23-10.36
2026-08-22-7.61
2026-08-21-5.91
2026-08-20-6.17
2026-08-19-8.43
2026-08-18-6.66
2026-08-17-5.19
2026-08-16-6.09
2026-08-15-8.12
2026-08-14-3.28
2026-08-13-4.88
2026-08-12-3.19
2026-08-11-2.61
2026-08-10-8.36
2026-08-09-1.30

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAT, lead day 8-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 0 days-12 to -10 °F: 1 day-10 to -8 °F: 4 days-8 to -6 °F: 6 days-6 to -4 °F: 7 days-4 to -2 °F: 5 days-2 to 0 °F: 3 days0 to 2 °F: 0 days2 to 4 °F: 2 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| 4.92 · P90 |e| 8.38 °F-200+20 °Fn = 28 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
-16.00-14.000
-14.00-12.000
-12.00-10.001
-10.00-8.004
-8.00-6.006
-6.00-4.007
-4.00-2.005
-2.00+0.003
+0.00+2.000
+2.00+4.002
+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
2026-08225.89 -5.89
2026-0162.27 -0.82

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-09 → 2026-08-30 28
GraphCast (IFS init)2026-01-09 → 2026-08-30 28
GraphCast (IFS init)2026-01-09 → 2026-08-30 27
GraphCast (IFS init)2026-01-09 → 2026-08-30 27

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 22 +3.16 [1.61, 3.91] yes
NCEP GFS 22 +3.91 [2.24, 4.95] yes
ECMWF IFS HRES 17 +3.30 [1.09, 4.26] yes
Persistence (baseline) 22 +3.71 [1.42, 5.22] yes

Cite this page

ShortCastCheck, KSAT graphcast_ifs lead 8, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSAT/model/graphcast_ifs/lead/8/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAT (San Antonio Intl), model graphcast_ifs, lead day 8. 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/8/

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