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

San Diego Lindbergh · GraphCast (IFS init) · lead day 0

KSAN · 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 QC5.43 [5.04, 5.86]0.89-5.43 [-5.86, -5.04]5.56 [5.12, 6.03]0% [0%, 0%]0%4%——2026-08-01 → 2026-08-30
tmax00Zbilinear90d28 1 QC5.43 [4.97, 5.90]0.89-5.43 [-5.90, -4.97]5.56 [5.09, 6.04]0% [0%, 0%]0%4%——2026-08-01 → 2026-08-30
tmax00Zbilinear365d34 1 QC5.12 [4.36, 5.73]1.00-5.12 [-5.73, -4.36]5.29 [4.52, 5.88]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmax00Zbilinearall34 1 QC5.12 [4.45, 5.70]1.00-5.12 [-5.70, -4.45]5.29 [4.63, 5.87]0% [0%, 0%]0%6%——2026-01-01 → 2026-08-30
tmax00Znearest30d28 1 QC7.71 [6.94, 8.64]1.23-7.71 [-8.64, -6.94]7.88 [7.05, 8.82]0% [0%, 0%]0%0%——2026-08-01 → 2026-08-30
tmax00Znearest90d28 1 QC7.71 [6.94, 8.66]1.23-7.71 [-8.66, -6.94]7.88 [7.04, 8.84]0% [0%, 0%]0%0%——2026-08-01 → 2026-08-30
tmax00Znearest365d34 1 QC6.99 [5.42, 8.35]1.69-6.99 [-8.35, -5.42]7.33 [5.84, 8.57]0% [0%, 0%]3%3%——2026-01-01 → 2026-08-30
tmax00Znearestall34 1 QC6.99 [5.52, 8.34]1.69-6.99 [-8.34, -5.52]7.33 [5.98, 8.57]0% [0%, 0%]3%3%——2026-01-01 → 2026-08-30
tmin00Zbilinear30d28 1 QC0.85 [0.65, 1.05]0.68-0.54 [-0.93, -0.04]1.02 [0.83, 1.20]61% [40%, 79%]96%100%——2026-08-01 → 2026-08-30
tmin00Zbilinear90d28 1 QC0.85 [0.62, 1.08]0.68-0.54 [-0.97, 0.02]1.02 [0.79, 1.23]61% [37%, 79%]96%100%——2026-08-01 → 2026-08-30
tmin00Zbilinear365d34 1 QC1.05 [0.72, 1.52]1.02-0.10 [-0.80, 0.94]1.37 [0.91, 1.91]56% [36%, 75%]85%97%——2026-01-01 → 2026-08-30
tmin00Zbilinearall34 1 QC1.05 [0.71, 1.52]1.02-0.10 [-0.80, 0.87]1.37 [0.92, 1.92]56% [35%, 75%]85%97%——2026-01-01 → 2026-08-30
tmin00Znearest30d28 1 QC0.68 [0.50, 0.85]0.65-0.22 [-0.55, 0.17]0.85 [0.65, 1.00]79% [65%, 90%]96%100%——2026-08-01 → 2026-08-30
tmin00Znearest90d28 1 QC0.68 [0.48, 0.86]0.65-0.22 [-0.57, 0.18]0.85 [0.61, 1.00]79% [60%, 93%]96%100%——2026-08-01 → 2026-08-30
tmin00Znearest365d34 1 QC1.05 [0.58, 1.84]1.11+0.32 [-0.44, 1.48]1.58 [0.75, 2.47]68% [41%, 88%]85%91%——2026-01-01 → 2026-08-30
tmin00Znearestall34 1 QC1.05 [0.59, 1.84]1.11+0.32 [-0.42, 1.44]1.58 [0.76, 2.49]68% [43%, 88%]85%91%——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 KSAN, lead day 0, 00Z bilinear tmax+10+50-5-102026-08-01: -5.92 °F2026-08-02: -6.11 °F2026-08-03: -5.23 °F2026-08-04: -4.46 °F2026-08-05: -6.37 °F2026-08-06: -5.27 °F2026-08-07: -4.46 °F2026-08-08: -4.92 °F2026-08-09: -7.22 °F2026-08-10: -6.2 °F2026-08-11: -5.42 °F2026-08-12: -4.64 °F2026-08-13: -4.01 °F2026-08-14: -4.78 °F2026-08-15: -4.59 °F2026-08-16: -4.39 °F2026-08-17: -5.68 °F2026-08-18: -5.22 °F2026-08-19: -4.7 °F2026-08-20: -6.79 °F2026-08-21: -5.36 °F2026-08-22: -4.87 °F2026-08-23: -9 °F2026-08-24: -5.79 °F2026-08-25: -6.28 °F2026-08-28: -4.79 °F2026-08-29: -6.89 °F2026-08-30: -2.77 °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
2026-08-30-2.77
2026-08-29-6.89
2026-08-28-4.79
2026-08-27—
2026-08-26—
2026-08-25-6.28
2026-08-24-5.79
2026-08-23-9.00
2026-08-22-4.87
2026-08-21-5.36
2026-08-20-6.79
2026-08-19-4.70
2026-08-18-5.22
2026-08-17-5.68
2026-08-16-4.39
2026-08-15-4.59
2026-08-14-4.78
2026-08-13-4.01
2026-08-12-4.64
2026-08-11-5.42
2026-08-10-6.20
2026-08-09-7.22
2026-08-08-4.92
2026-08-07-4.46
2026-08-06-5.27
2026-08-05-6.37
2026-08-04-4.46
2026-08-03-5.23
2026-08-02-6.11
2026-08-01-5.92

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAN, lead day 0-10 to -9 °F: 0 days-9 to -8 °F: 1 day-8 to -7 °F: 1 day-7 to -6 °F: 6 days-6 to -5 °F: 9 days-5 to -4 °F: 12 days-4 to -3 °F: 3 days-3 to -2 °F: 2 days-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| 5.07 · P90 |e| 6.66 °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
-10.00-9.000
-9.00-8.001
-8.00-7.001
-7.00-6.006
-6.00-5.009
-5.00-4.0012
-4.00-3.003
-3.00-2.002
-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
2026-08285.43 -5.43
2026-0163.66 -3.66

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 +1.47 [0.99, 1.97] yes
Aurora (GFS init) 2 -0.95 [-1.45, -0.45] yes
Aurora (IFS init) 3 +0.14 [-0.75, 1.03] no
FourCastNet v2 (GFS init) 2 +1.90 [1.43, 2.37] yes
FourCastNet v2 (IFS init) 3 +2.13 [1.26, 3.30] yes
NCEP GFS 28 +2.67 [1.89, 3.39] yes
GraphCast (GFS init) 2 -0.47 [-0.85, -0.10] yes
ECMWF IFS HRES 23 -0.17 [-0.53, 0.19] no
Pangu-Weather (GFS init) 2 -0.55 [-0.88, -0.22] yes
Pangu-Weather (IFS init) 3 -0.70 [-1.41, 0.54] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAN (San Diego Lindbergh), 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/KSAN/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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