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

San Diego Lindbergh · GraphCast (IFS init) · lead day 2

KSAN · graphcast_ifs · lead 2

Target day = initialization date + 2 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
tmax00Zbilinear30d26 1 QC5.72 [4.99, 6.55]1.09-5.72 [-6.55, -4.99]5.92 [5.10, 6.83]0% [0%, 0%]0%0%-1.70+0.482026-08-03 → 2026-08-30
tmax00Zbilinear90d26 1 QC5.72 [4.95, 6.59]1.09-5.72 [-6.59, -4.95]5.92 [5.02, 6.83]0% [0%, 0%]0%0%-1.70+0.482026-08-03 → 2026-08-30
tmax00Zbilinear365d32 1 QC5.38 [4.44, 6.30]1.14-5.38 [-6.30, -4.44]5.60 [4.58, 6.57]0% [0%, 0%]0%3%-1.69+0.432026-01-03 → 2026-08-30
tmax00Zbilinearall32 1 QC5.38 [4.48, 6.30]1.14-5.38 [-6.30, -4.48]5.60 [4.60, 6.57]0% [0%, 0%]0%3%-1.69+0.432026-01-03 → 2026-08-30
tmax00Znearest30d26 1 QC7.66 [6.62, 8.85]1.35-7.66 [-8.85, -6.62]7.89 [6.71, 9.16]0% [0%, 0%]0%0%-2.62+0.362026-08-03 → 2026-08-30
tmax00Znearest90d26 1 QC7.66 [6.55, 8.91]1.35-7.66 [-8.91, -6.55]7.89 [6.66, 9.21]0% [0%, 0%]0%0%-2.62+0.362026-08-03 → 2026-08-30
tmax00Znearest365d32 1 QC6.91 [5.15, 8.46]1.75-6.91 [-8.46, -5.15]7.29 [5.50, 8.79]0% [0%, 0%]0%3%-2.45+0.122026-01-03 → 2026-08-30
tmax00Znearestall32 1 QC6.91 [5.20, 8.46]1.75-6.91 [-8.46, -5.20]7.29 [5.54, 8.81]0% [0%, 0%]0%3%-2.45+0.122026-01-03 → 2026-08-30
tmax12Zbilinear30d26 1 QC5.61 [5.00, 6.33]1.04-5.61 [-6.33, -5.00]5.79 [5.09, 6.61]0% [0%, 0%]0%0%-1.65+0.502026-08-03 → 2026-08-30
tmax12Zbilinear90d26 1 QC5.61 [4.95, 6.34]1.04-5.61 [-6.34, -4.95]5.79 [5.03, 6.61]0% [0%, 0%]0%0%-1.65+0.502026-08-03 → 2026-08-30
tmax12Zbilinear365d31 1 QC5.31 [4.44, 6.07]1.13-5.31 [-6.07, -4.44]5.52 [4.56, 6.35]0% [0%, 0%]0%0%-1.66+0.442026-01-03 → 2026-08-30
tmax12Zbilinearall31 1 QC5.31 [4.50, 6.09]1.13-5.31 [-6.09, -4.50]5.52 [4.58, 6.35]0% [0%, 0%]0%0%-1.66+0.442026-01-03 → 2026-08-30
tmax12Znearest30d26 1 QC7.60 [6.66, 8.73]1.33-7.60 [-8.73, -6.66]7.81 [6.75, 9.08]0% [0%, 0%]0%0%-2.59+0.372026-08-03 → 2026-08-30
tmax12Znearest90d26 1 QC7.60 [6.57, 8.84]1.33-7.60 [-8.84, -6.57]7.81 [6.65, 9.07]0% [0%, 0%]0%0%-2.59+0.372026-08-03 → 2026-08-30
tmax12Znearest365d31 1 QC6.96 [5.24, 8.39]1.68-6.96 [-8.39, -5.24]7.30 [5.60, 8.74]0% [0%, 0%]0%3%-2.48+0.162026-01-03 → 2026-08-30
tmax12Znearestall31 1 QC6.96 [5.33, 8.34]1.68-6.96 [-8.34, -5.33]7.30 [5.69, 8.67]0% [0%, 0%]0%3%-2.48+0.162026-01-03 → 2026-08-30
tmin00Zbilinear30d26 1 QC1.02 [0.76, 1.39]0.86-0.65 [-1.19, -0.13]1.26 [0.95, 1.63]46% [27%, 62%]85%96%-0.02+0.192026-08-03 → 2026-08-30
tmin00Zbilinear90d26 1 QC1.02 [0.74, 1.47]0.86-0.65 [-1.27, -0.14]1.26 [0.94, 1.71]46% [25%, 62%]85%96%-0.02+0.192026-08-03 → 2026-08-30
tmin00Zbilinear365d32 1 QC1.35 [0.81, 2.16]1.34-0.01 [-0.99, 1.36]1.72 [1.02, 2.50]41% [20%, 59%]72%88%+0.06+0.122026-01-03 → 2026-08-30
tmin00Zbilinearall32 1 QC1.35 [0.87, 2.17]1.34-0.01 [-0.98, 1.36]1.72 [1.07, 2.53]41% [18%, 60%]72%88%+0.06+0.122026-01-03 → 2026-08-30
tmin00Znearest30d26 1 QC0.86 [0.57, 1.12]0.86+0.13 [-0.46, 0.63]1.11 [0.70, 1.37]69% [54%, 87%]88%100%+0.14+0.182026-08-03 → 2026-08-30
tmin00Znearest90d26 1 QC0.86 [0.56, 1.15]0.86+0.13 [-0.55, 0.64]1.11 [0.69, 1.39]69% [50%, 88%]88%100%+0.14+0.182026-08-03 → 2026-08-30
tmin00Znearest365d32 1 QC1.47 [0.71, 2.84]1.48+0.87 [-0.23, 2.51]2.13 [0.91, 3.42]56% [21%, 80%]75%84%-0.02+0.032026-01-03 → 2026-08-30
tmin00Znearestall32 1 QC1.47 [0.70, 2.86]1.48+0.87 [-0.24, 2.46]2.13 [0.90, 3.53]56% [24%, 79%]75%84%-0.02+0.032026-01-03 → 2026-08-30
tmin12Zbilinear30d26 1 QC1.09 [0.78, 1.48]0.93-0.61 [-1.25, -0.01]1.34 [1.01, 1.70]54% [30%, 74%]88%96%-0.09+0.122026-08-03 → 2026-08-30
tmin12Zbilinear90d26 1 QC1.09 [0.76, 1.58]0.93-0.61 [-1.33, -0.00]1.34 [1.00, 1.75]54% [26%, 78%]88%96%-0.09+0.122026-08-03 → 2026-08-30
tmin12Zbilinear365d31 1 QC1.31 [0.85, 1.97]1.28-0.12 [-1.04, 1.13]1.65 [1.09, 2.28]48% [24%, 71%]77%90%+0.03+0.102026-01-03 → 2026-08-30
tmin12Zbilinearall31 1 QC1.31 [0.89, 2.05]1.28-0.12 [-1.08, 1.03]1.65 [1.13, 2.32]48% [21%, 72%]77%90%+0.03+0.102026-01-03 → 2026-08-30
tmin12Znearest30d26 1 QC0.94 [0.67, 1.17]0.93+0.18 [-0.47, 0.76]1.23 [0.81, 1.51]62% [44%, 77%]88%96%+0.06+0.122026-08-03 → 2026-08-30
tmin12Znearest90d26 1 QC0.94 [0.66, 1.21]0.93+0.18 [-0.57, 0.77]1.23 [0.81, 1.53]62% [42%, 81%]88%96%+0.06+0.122026-08-03 → 2026-08-30
tmin12Znearest365d31 1 QC1.37 [0.75, 2.43]1.39+0.74 [-0.22, 2.05]1.92 [0.97, 2.99]52% [25%, 74%]77%84%-0.01+0.032026-01-03 → 2026-08-30
tmin12Znearestall31 1 QC1.37 [0.77, 2.46]1.39+0.74 [-0.29, 1.99]1.92 [0.93, 3.04]52% [24%, 75%]77%84%-0.01+0.032026-01-03 → 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 2, 00Z bilinear tmax+20+100-10-202026-08-03: -5.02 °F2026-08-04: -4.86 °F2026-08-05: -6.61 °F2026-08-06: -6.28 °F2026-08-07: -5.51 °F2026-08-08: -4.78 °F2026-08-09: -5.39 °F2026-08-10: -6.66 °F2026-08-11: -6.14 °F2026-08-12: -5.24 °F2026-08-13: -3.41 °F2026-08-14: -4.33 °F2026-08-15: -5.09 °F2026-08-16: -4.67 °F2026-08-17: -5.09 °F2026-08-18: -4.2 °F2026-08-19: -4.65 °F2026-08-20: -7.32 °F2026-08-21: -6.46 °F2026-08-22: -5.69 °F2026-08-23: -9.13 °F2026-08-24: -5.76 °F2026-08-25: -6.4 °F2026-08-26: -10.57 °F2026-08-27: -5.68 °F2026-08-30: -3.71 °F2026-08-032026-08-30°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 (28 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-3.71
2026-08-29—
2026-08-28—
2026-08-27-5.68
2026-08-26-10.57
2026-08-25-6.40
2026-08-24-5.76
2026-08-23-9.13
2026-08-22-5.69
2026-08-21-6.46
2026-08-20-7.32
2026-08-19-4.65
2026-08-18-4.20
2026-08-17-5.09
2026-08-16-4.67
2026-08-15-5.09
2026-08-14-4.33
2026-08-13-3.41
2026-08-12-5.24
2026-08-11-6.14
2026-08-10-6.66
2026-08-09-5.39
2026-08-08-4.78
2026-08-07-5.51
2026-08-06-6.28
2026-08-05-6.61
2026-08-04-4.86
2026-08-03-5.02

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAN, lead day 2-20 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: 1 day-8 to -6 °F: 7 days-6 to -4 °F: 17 days-4 to -2 °F: 6 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| 5.17 · P90 |e| 6.66 °F-200+20 °Fn = 32 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
-10.00-8.001
-8.00-6.007
-6.00-4.0017
-4.00-2.006
-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
2026-08265.72 -5.72
2026-0163.91 -3.91

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-03 → 2026-08-30 32
GraphCast (IFS init)2026-01-03 → 2026-08-30 32
GraphCast (IFS init)2026-01-03 → 2026-08-30 31
GraphCast (IFS init)2026-01-03 → 2026-08-30 31

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 26 +2.07 [1.23, 3.22] yes
Aurora (IFS init) 1 -0.14 [-0.14, -0.14] yes
FourCastNet v2 (IFS init) 1 +3.17 [3.17, 3.17] yes
NCEP GFS 26 +2.90 [2.02, 3.75] yes
ECMWF IFS HRES 21 -0.01 [-0.67, 0.85] no
Pangu-Weather (IFS init) 1 -1.14 [-1.14, -1.14] yes
Persistence (baseline) 26 +3.60 [2.80, 4.14] yes

Cite this page

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

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

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