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

San Diego Lindbergh · GraphCast (IFS init) · lead day 5

KSAN · graphcast_ifs · lead 5

Target day = initialization date + 5 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
tmax00Zbilinear30d25 1 QC5.60 [4.39, 6.88]1.57-5.60 [-6.88, -4.39]6.01 [4.59, 7.30]0% [0%, 0%]4%4%-0.84+0.452026-08-06 → 2026-08-30
tmax00Zbilinear90d25 1 QC5.60 [4.35, 6.94]1.57-5.60 [-6.94, -4.35]6.01 [4.52, 7.37]0% [0%, 0%]4%4%-0.84+0.452026-08-06 → 2026-08-30
tmax00Zbilinear365d31 1 QC5.22 [4.04, 6.60]1.62-5.22 [-6.60, -4.04]5.66 [4.27, 7.05]0% [0%, 0%]3%13%-0.65+0.462026-01-06 → 2026-08-30
tmax00Zbilinearall31 1 QC5.22 [3.95, 6.59]1.62-5.22 [-6.59, -3.95]5.66 [4.15, 7.07]0% [0%, 0%]3%13%-0.65+0.462026-01-06 → 2026-08-30
tmax00Znearest30d25 1 QC7.56 [6.05, 9.10]1.71-7.56 [-9.10, -6.05]7.93 [6.26, 9.50]0% [0%, 0%]0%0%-1.49+0.402026-08-06 → 2026-08-30
tmax00Znearest90d25 1 QC7.56 [5.96, 9.31]1.71-7.56 [-9.31, -5.96]7.93 [6.11, 9.63]0% [0%, 0%]0%0%-1.49+0.402026-08-06 → 2026-08-30
tmax00Znearest365d31 1 QC6.81 [4.96, 8.78]2.04-6.81 [-8.78, -4.96]7.33 [5.31, 9.13]0% [0%, 0%]0%10%-1.15+0.322026-01-06 → 2026-08-30
tmax00Znearestall31 1 QC6.81 [4.80, 8.69]2.04-6.81 [-8.69, -4.80]7.33 [5.18, 9.13]0% [0%, 0%]0%10%-1.15+0.322026-01-06 → 2026-08-30
tmax12Zbilinear30d25 1 QC5.57 [4.55, 6.66]1.42-5.57 [-6.66, -4.55]5.91 [4.76, 6.98]0% [0%, 0%]4%4%-0.83+0.502026-08-06 → 2026-08-30
tmax12Zbilinear90d25 1 QC5.57 [4.49, 6.74]1.42-5.57 [-6.74, -4.49]5.91 [4.70, 7.05]0% [0%, 0%]4%4%-0.83+0.502026-08-06 → 2026-08-30
tmax12Zbilinear365d30 1 QC5.20 [4.07, 6.40]1.47-5.20 [-6.40, -4.07]5.58 [4.29, 6.78]0% [0%, 0%]7%7%-0.73+0.492026-01-06 → 2026-08-30
tmax12Zbilinearall30 1 QC5.20 [3.97, 6.40]1.47-5.20 [-6.40, -3.97]5.58 [4.20, 6.74]0% [0%, 0%]7%7%-0.73+0.492026-01-06 → 2026-08-30
tmax12Znearest30d25 1 QC7.61 [6.29, 9.05]1.58-7.61 [-9.05, -6.29]7.93 [6.52, 9.33]0% [0%, 0%]0%0%-1.50+0.442026-08-06 → 2026-08-30
tmax12Znearest90d25 1 QC7.61 [6.21, 9.26]1.58-7.61 [-9.26, -6.21]7.93 [6.38, 9.53]0% [0%, 0%]0%0%-1.50+0.442026-08-06 → 2026-08-30
tmax12Znearest365d30 1 QC6.91 [5.06, 8.77]1.95-6.91 [-8.77, -5.06]7.38 [5.46, 9.08]0% [0%, 0%]3%3%-1.30+0.332026-01-06 → 2026-08-30
tmax12Znearestall30 1 QC6.91 [4.92, 8.68]1.95-6.91 [-8.68, -4.92]7.38 [5.37, 9.01]0% [0%, 0%]3%3%-1.30+0.332026-01-06 → 2026-08-30
tmin00Zbilinear30d25 1 QC0.58 [0.32, 1.09]0.60-0.25 [-0.83, 0.04]0.88 [0.39, 1.48]88% [62%, 100%]92%100%+0.62+0.562026-08-06 → 2026-08-30
tmin00Zbilinear90d25 1 QC0.58 [0.31, 1.18]0.60-0.25 [-0.97, 0.07]0.88 [0.38, 1.56]88% [56%, 100%]92%100%+0.62+0.562026-08-06 → 2026-08-30
tmin00Zbilinear365d31 1 QC2.12 [0.43, 5.65]2.75+1.46 [-0.48, 5.01]4.35 [0.62, 7.84]71% [29%, 96%]74%81%+0.38+0.292026-01-06 → 2026-08-30
tmin00Zbilinearall31 1 QC2.12 [0.42, 6.12]2.75+1.46 [-0.47, 5.56]4.35 [0.60, 8.13]71% [19%, 95%]74%81%+0.38+0.292026-01-06 → 2026-08-30
tmin00Znearest30d25 1 QC0.94 [0.76, 1.17]0.71+0.56 [-0.15, 0.97]1.10 [0.91, 1.33]56% [40%, 70%]96%100%+0.38+0.492026-08-06 → 2026-08-30
tmin00Znearest90d25 1 QC0.94 [0.75, 1.18]0.71+0.56 [-0.36, 1.00]1.10 [0.90, 1.33]56% [42%, 71%]96%100%+0.38+0.492026-08-06 → 2026-08-30
tmin00Znearest365d31 1 QC2.73 [0.86, 6.63]3.00+2.42 [0.27, 6.36]5.05 [1.02, 8.92]45% [18%, 64%]77%81%+0.20+0.222026-01-06 → 2026-08-30
tmin00Znearestall31 1 QC2.73 [0.83, 7.26]3.00+2.42 [0.27, 6.89]5.05 [0.99, 9.37]45% [16%, 64%]77%81%+0.20+0.222026-01-06 → 2026-08-30
tmin12Zbilinear30d25 1 QC0.82 [0.58, 1.34]0.84-0.30 [-0.99, 0.16]1.10 [0.72, 1.67]72% [44%, 87%]88%100%+0.46+0.392026-08-06 → 2026-08-30
tmin12Zbilinear90d25 1 QC0.82 [0.56, 1.48]0.84-0.30 [-1.15, 0.19]1.10 [0.70, 1.77]72% [35%, 86%]88%100%+0.46+0.392026-08-06 → 2026-08-30
tmin12Zbilinear365d30 1 QC1.94 [0.62, 4.66]2.22+1.00 [-0.68, 3.94]3.60 [0.82, 6.43]60% [20%, 83%]73%83%+0.38+0.372026-01-06 → 2026-08-30
tmin12Zbilinearall30 1 QC1.94 [0.64, 5.23]2.22+1.00 [-0.65, 4.54]3.60 [0.83, 6.88]60% [9%, 82%]73%83%+0.38+0.372026-01-06 → 2026-08-30
tmin12Znearest30d25 1 QC1.06 [0.77, 1.39]0.90+0.50 [-0.30, 1.04]1.25 [0.96, 1.53]52% [28%, 75%]92%100%+0.30+0.352026-08-06 → 2026-08-30
tmin12Znearest90d25 1 QC1.06 [0.78, 1.42]0.90+0.50 [-0.58, 1.07]1.25 [0.99, 1.56]52% [25%, 74%]92%100%+0.30+0.352026-08-06 → 2026-08-30
tmin12Znearest365d30 1 QC2.38 [0.89, 5.44]2.41+1.92 [0.08, 5.11]4.22 [1.09, 7.47]43% [12%, 67%]77%83%+0.24+0.312026-01-06 → 2026-08-30
tmin12Znearestall30 1 QC2.38 [0.88, 6.30]2.41+1.92 [0.14, 5.73]4.22 [1.09, 8.03]43% [10%, 68%]77%83%+0.24+0.312026-01-06 → 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 5, 00Z bilinear tmax+20+100-10-202026-08-06: -6.51 °F2026-08-07: -5.4 °F2026-08-08: -5.74 °F2026-08-09: -5.74 °F2026-08-10: -6.13 °F2026-08-11: -4.35 °F2026-08-12: -3.97 °F2026-08-13: -2 °F2026-08-14: -3.32 °F2026-08-15: -4.5 °F2026-08-16: -3.91 °F2026-08-17: -4.76 °F2026-08-18: -3.59 °F2026-08-19: -3.77 °F2026-08-20: -5.82 °F2026-08-21: -6.39 °F2026-08-22: -6.78 °F2026-08-23: -11.78 °F2026-08-24: -5.21 °F2026-08-25: -6.56 °F2026-08-26: -10.75 °F2026-08-27: -4.16 °F2026-08-28: -5.53 °F2026-08-29: -8.99 °F2026-08-30: -4.39 °F2026-08-062026-08-30°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 (25 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-4.39
2026-08-29-8.99
2026-08-28-5.53
2026-08-27-4.16
2026-08-26-10.75
2026-08-25-6.56
2026-08-24-5.21
2026-08-23-11.78
2026-08-22-6.78
2026-08-21-6.39
2026-08-20-5.82
2026-08-19-3.77
2026-08-18-3.59
2026-08-17-4.76
2026-08-16-3.91
2026-08-15-4.50
2026-08-14-3.32
2026-08-13-2.00
2026-08-12-3.97
2026-08-11-4.35
2026-08-10-6.13
2026-08-09-5.74
2026-08-08-5.74
2026-08-07-5.40
2026-08-06-6.51

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAN, lead day 5-20 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: 2 days-10 to -8 °F: 1 day-8 to -6 °F: 6 days-6 to -4 °F: 12 days-4 to -2 °F: 9 days-2 to 0 °F: 1 day0 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| 4.76 · P90 |e| 6.78 °F-200+20 °Fn = 31 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
-12.00-10.002
-10.00-8.001
-8.00-6.006
-6.00-4.0012
-4.00-2.009
-2.00+0.001
+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
2026-08255.60 -5.60
2026-0163.63 -3.63

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-06 → 2026-08-30 31
GraphCast (IFS init)2026-01-06 → 2026-08-30 31
GraphCast (IFS init)2026-01-06 → 2026-08-30 30
GraphCast (IFS init)2026-01-06 → 2026-08-30 30

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 25 +2.12 [1.43, 2.90] yes
NCEP GFS 25 +2.28 [1.13, 3.48] yes
ECMWF IFS HRES 18 -0.05 [-1.16, 1.46] no
Persistence (baseline) 25 +2.56 [1.62, 3.64] yes

Cite this page

ShortCastCheck, KSAN graphcast_ifs lead 5, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSAN/model/graphcast_ifs/lead/5/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAN (San Diego Lindbergh), model graphcast_ifs, lead day 5. 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/5/

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