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

San Diego Lindbergh · GraphCast (IFS init) · lead day 8

KSAN · 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 QC5.91 [3.88, 8.12]2.66-5.91 [-8.12, -3.88]6.80 [4.30, 8.84]5% [0%, 19%]14%18%-0.63+0.192026-08-09 → 2026-08-30
tmax00Zbilinear90d22 1 QC5.91 [3.76, 8.33]2.66-5.91 [-8.33, -3.76]6.80 [4.18, 9.00]5% [0%, 22%]14%18%-0.63+0.192026-08-09 → 2026-08-30
tmax00Zbilinear365d28 1 QC5.55 [3.80, 7.62]2.48-5.51 [-7.62, -3.71]6.40 [4.20, 8.38]7% [0%, 20%]14%21%-0.40+0.282026-01-09 → 2026-08-30
tmax00Zbilinearall28 1 QC5.55 [3.71, 7.99]2.48-5.51 [-7.99, -3.62]6.40 [4.13, 8.68]7% [0%, 22%]14%21%-0.40+0.282026-01-09 → 2026-08-30
tmax00Znearest30d22 1 QC7.55 [5.34, 9.93]2.62-7.55 [-9.93, -5.34]8.25 [5.66, 10.44]0% [0%, 0%]0%5%-1.08+0.202026-08-09 → 2026-08-30
tmax00Znearest90d22 1 QC7.55 [5.19, 10.12]2.62-7.55 [-10.12, -5.19]8.25 [5.48, 10.58]0% [0%, 0%]0%5%-1.08+0.202026-08-09 → 2026-08-30
tmax00Znearest365d28 1 QC7.03 [5.11, 9.24]2.54-7.03 [-9.24, -5.11]7.75 [5.43, 9.84]4% [0%, 13%]4%7%-0.77+0.262026-01-09 → 2026-08-30
tmax00Znearestall28 1 QC7.03 [4.95, 9.65]2.54-7.03 [-9.65, -4.95]7.75 [5.31, 10.16]4% [0%, 14%]4%7%-0.77+0.262026-01-09 → 2026-08-30
tmax12Zbilinear30d22 1 QC5.46 [3.82, 7.17]2.25-5.46 [-7.17, -3.82]6.15 [4.28, 7.75]5% [0%, 19%]9%14%-0.50+0.322026-08-09 → 2026-08-30
tmax12Zbilinear90d22 1 QC5.46 [3.75, 7.32]2.25-5.46 [-7.32, -3.75]6.15 [4.22, 7.90]5% [0%, 22%]9%14%-0.50+0.322026-08-09 → 2026-08-30
tmax12Zbilinear365d27 1 QC5.05 [3.50, 6.73]2.26-4.98 [-6.67, -3.34]5.76 [3.90, 7.41]7% [0%, 22%]11%15%-0.34+0.322026-01-09 → 2026-08-30
tmax12Zbilinearall27 1 QC5.05 [3.33, 6.98]2.26-4.98 [-6.98, -3.09]5.76 [3.69, 7.66]7% [0%, 25%]11%15%-0.34+0.322026-01-09 → 2026-08-30
tmax12Znearest30d22 1 QC7.25 [5.42, 9.09]2.19-7.25 [-9.09, -5.42]7.79 [5.71, 9.55]0% [0%, 0%]0%5%-0.99+0.332026-08-09 → 2026-08-30
tmax12Znearest90d22 1 QC7.25 [5.36, 9.24]2.19-7.25 [-9.24, -5.36]7.79 [5.62, 9.67]0% [0%, 0%]0%5%-0.99+0.332026-08-09 → 2026-08-30
tmax12Znearest365d27 1 QC6.56 [4.46, 8.56]2.39-6.56 [-8.56, -4.46]7.24 [4.99, 9.10]4% [0%, 14%]4%7%-0.74+0.282026-01-09 → 2026-08-30
tmax12Znearestall27 1 QC6.56 [4.27, 8.96]2.39-6.56 [-8.96, -4.27]7.24 [4.73, 9.42]4% [0%, 15%]4%7%-0.74+0.282026-01-09 → 2026-08-30
tmin00Zbilinear30d22 1 QC1.07 [0.73, 1.38]1.10-0.13 [-0.93, 0.59]1.36 [0.90, 1.75]68% [56%, 83%]82%95%+0.38+0.332026-08-09 → 2026-08-30
tmin00Zbilinear90d22 1 QC1.07 [0.70, 1.41]1.10-0.13 [-1.04, 0.63]1.36 [0.84, 1.78]68% [56%, 88%]82%95%+0.38+0.332026-08-09 → 2026-08-30
tmin00Zbilinear365d28 1 QC3.88 [0.89, 9.54]4.83+2.94 [-0.69, 9.42]6.77 [1.08, 11.67]54% [23%, 76%]64%75%+0.14+0.082026-01-09 → 2026-08-30
tmin00Zbilinearall28 1 QC3.88 [0.91, 10.61]4.83+2.94 [-0.61, 10.49]6.77 [1.11, 12.37]54% [18%, 75%]64%75%+0.14+0.082026-01-09 → 2026-08-30
tmin00Znearest30d22 1 QC1.37 [0.92, 1.71]1.12+0.75 [-0.09, 1.55]1.56 [1.09, 1.89]36% [17%, 60%]82%100%+0.21+0.322026-08-09 → 2026-08-30
tmin00Znearest90d22 1 QC1.37 [0.79, 1.74]1.12+0.75 [-0.19, 1.59]1.56 [0.90, 1.88]36% [14%, 64%]82%100%+0.21+0.322026-08-09 → 2026-08-30
tmin00Znearest365d28 1 QC4.44 [1.15, 10.63]5.03+3.95 [0.13, 10.62]7.47 [1.35, 12.71]29% [7%, 52%]64%79%+0.02+0.052026-01-09 → 2026-08-30
tmin00Znearestall28 1 QC4.44 [1.18, 11.83]5.03+3.95 [0.25, 11.83]7.47 [1.35, 13.62]29% [6%, 50%]64%79%+0.02+0.052026-01-09 → 2026-08-30
tmin12Zbilinear30d22 1 QC0.71 [0.55, 0.85]0.65+0.17 [-0.28, 0.57]0.83 [0.64, 0.99]77% [61%, 91%]100%100%+0.59+0.612026-08-09 → 2026-08-30
tmin12Zbilinear90d22 1 QC0.71 [0.53, 0.86]0.65+0.17 [-0.34, 0.58]0.83 [0.62, 1.01]77% [57%, 92%]100%100%+0.59+0.612026-08-09 → 2026-08-30
tmin12Zbilinear365d27 1 QC3.26 [0.62, 8.95]4.32+2.82 [-0.15, 8.75]6.35 [0.71, 11.35]63% [29%, 86%]81%81%+0.27+0.182026-01-09 → 2026-08-30
tmin12Zbilinearall27 1 QC3.26 [0.63, 10.28]4.32+2.82 [-0.13, 10.28]6.35 [0.73, 12.17]63% [22%, 86%]81%81%+0.27+0.182026-01-09 → 2026-08-30
tmin12Znearest30d22 1 QC1.20 [0.80, 1.54]0.64+1.06 [0.54, 1.51]1.32 [0.93, 1.60]32% [8%, 59%]95%100%+0.30+0.612026-08-09 → 2026-08-30
tmin12Znearest90d22 1 QC1.20 [0.75, 1.54]0.64+1.06 [0.50, 1.54]1.32 [0.86, 1.60]32% [5%, 62%]95%100%+0.30+0.612026-08-09 → 2026-08-30
tmin12Znearest365d27 1 QC3.93 [0.96, 9.98]4.49+3.82 [0.68, 9.93]7.01 [1.09, 12.45]26% [0%, 52%]78%81%+0.12+0.152026-01-09 → 2026-08-30
tmin12Znearestall27 1 QC3.93 [0.99, 11.45]4.49+3.82 [0.73, 11.45]7.01 [1.11, 13.37]26% [0%, 50%]78%81%+0.12+0.152026-01-09 → 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 KSAN, lead day 8, 00Z bilinear tmax+20+100-10-202026-08-09: -8.04 °F2026-08-10: -6.92 °F2026-08-11: -5.28 °F2026-08-12: -3.99 °F2026-08-13: -1.67 °F2026-08-14: -3.59 °F2026-08-15: -1.81 °F2026-08-16: -3.5 °F2026-08-17: -4.34 °F2026-08-18: -2.45 °F2026-08-19: -4.62 °F2026-08-20: -6.32 °F2026-08-21: -5.9 °F2026-08-22: -6.64 °F2026-08-23: -13.26 °F2026-08-24: -10.18 °F2026-08-25: -10.29 °F2026-08-26: -13.01 °F2026-08-27: -5.44 °F2026-08-28: -4.48 °F2026-08-29: -7.78 °F2026-08-30: -0.6 °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
2026-08-30-0.60
2026-08-29-7.78
2026-08-28-4.48
2026-08-27-5.44
2026-08-26-13.01
2026-08-25-10.29
2026-08-24-10.18
2026-08-23-13.26
2026-08-22-6.64
2026-08-21-5.90
2026-08-20-6.32
2026-08-19-4.62
2026-08-18-2.45
2026-08-17-4.34
2026-08-16-3.50
2026-08-15-1.81
2026-08-14-3.59
2026-08-13-1.67
2026-08-12-3.99
2026-08-11-5.28
2026-08-10-6.92
2026-08-09-8.04

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAN, 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: 2 days-12 to -10 °F: 2 days-10 to -8 °F: 1 day-8 to -6 °F: 6 days-6 to -4 °F: 8 days-4 to -2 °F: 5 days-2 to 0 °F: 3 days0 to 2 °F: 1 day2 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| 5.09 · P90 |e| 10.21 °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
-14.00-12.002
-12.00-10.002
-10.00-8.001
-8.00-6.006
-6.00-4.008
-4.00-2.005
-2.00+0.003
+0.00+2.001
+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
2026-08225.91 -5.91
2026-0164.20 -4.01

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 +2.33 [1.03, 3.77] yes
NCEP GFS 22 +2.09 [0.51, 3.84] yes
ECMWF IFS HRES 17 +0.11 [-1.47, 1.88] no
Persistence (baseline) 22 +2.28 [0.95, 3.76] yes

Cite this page

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

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