Raw model output on the native 0.25° grid — no MOS, no bias correction, no post-processing. Scores understate operational forecast quality. Read the fairness statement →

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

San Diego Lindbergh · GraphCast (IFS init) · lead day 6

KSAN · graphcast_ifs · lead 6

Target day = initialization date + 6 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
tmax00Zbilinear30d24 1 QC5.58 [4.15, 7.05]1.77-5.58 [-7.05, -4.15]6.09 [4.39, 7.57]0% [0%, 0%]4%4%-0.81+0.392026-08-07 → 2026-08-30
tmax00Zbilinear90d24 1 QC5.58 [4.09, 7.13]1.77-5.58 [-7.13, -4.09]6.09 [4.34, 7.60]0% [0%, 0%]4%4%-0.81+0.392026-08-07 → 2026-08-30
tmax00Zbilinear365d30 1 QC4.99 [3.39, 6.71]1.90-4.99 [-6.71, -3.39]5.59 [3.70, 7.22]3% [0%, 12%]10%13%-0.54+0.392026-01-07 → 2026-08-30
tmax00Zbilinearall30 1 QC4.99 [3.30, 6.77]1.90-4.99 [-6.77, -3.30]5.59 [3.66, 7.27]3% [0%, 12%]10%13%-0.54+0.392026-01-07 → 2026-08-30
tmax00Znearest30d24 1 QC7.44 [5.71, 9.22]1.87-7.44 [-9.22, -5.71]7.89 [5.97, 9.60]0% [0%, 0%]0%4%-1.41+0.362026-08-07 → 2026-08-30
tmax00Znearest90d24 1 QC7.44 [5.66, 9.37]1.87-7.44 [-9.37, -5.66]7.89 [5.86, 9.71]0% [0%, 0%]0%4%-1.41+0.362026-08-07 → 2026-08-30
tmax00Znearest365d30 1 QC6.56 [4.36, 8.71]2.28-6.56 [-8.71, -4.36]7.21 [4.82, 9.22]0% [0%, 0%]3%13%-1.03+0.272026-01-07 → 2026-08-30
tmax00Znearestall30 1 QC6.56 [4.19, 8.76]2.28-6.56 [-8.76, -4.19]7.21 [4.67, 9.23]0% [0%, 0%]3%13%-1.03+0.272026-01-07 → 2026-08-30
tmax12Zbilinear30d24 1 QC5.39 [4.12, 6.69]1.58-5.39 [-6.69, -4.12]5.82 [4.34, 7.09]0% [0%, 0%]4%12%-0.75+0.462026-08-07 → 2026-08-30
tmax12Zbilinear90d24 1 QC5.39 [4.04, 6.73]1.58-5.39 [-6.73, -4.04]5.82 [4.27, 7.15]0% [0%, 0%]4%12%-0.75+0.462026-08-07 → 2026-08-30
tmax12Zbilinear365d29 1 QC4.98 [3.63, 6.44]1.65-4.98 [-6.44, -3.63]5.48 [3.95, 6.88]0% [0%, 0%]10%21%-0.57+0.462026-01-07 → 2026-08-30
tmax12Zbilinearall29 1 QC4.98 [3.60, 6.46]1.65-4.98 [-6.46, -3.60]5.48 [3.85, 6.86]0% [0%, 0%]10%21%-0.57+0.462026-01-07 → 2026-08-30
tmax12Znearest30d24 1 QC7.38 [5.82, 9.00]1.70-7.38 [-9.00, -5.82]7.78 [6.01, 9.35]0% [0%, 0%]0%4%-1.39+0.422026-08-07 → 2026-08-30
tmax12Znearest90d24 1 QC7.38 [5.72, 9.22]1.70-7.38 [-9.22, -5.72]7.78 [5.89, 9.53]0% [0%, 0%]0%4%-1.39+0.422026-08-07 → 2026-08-30
tmax12Znearest365d29 1 QC6.71 [4.76, 8.72]2.04-6.71 [-8.72, -4.76]7.26 [5.18, 9.11]0% [0%, 0%]3%10%-1.11+0.342026-01-07 → 2026-08-30
tmax12Znearestall29 1 QC6.71 [4.62, 8.69]2.04-6.71 [-8.69, -4.62]7.26 [5.09, 9.05]0% [0%, 0%]3%10%-1.11+0.342026-01-07 → 2026-08-30
tmin00Zbilinear30d24 1 QC0.74 [0.55, 1.03]0.74-0.04 [-0.57, 0.28]0.95 [0.67, 1.33]75% [55%, 88%]96%100%+0.58+0.542026-08-07 → 2026-08-30
tmin00Zbilinear90d24 1 QC0.74 [0.55, 1.13]0.74-0.04 [-0.73, 0.29]0.95 [0.68, 1.41]75% [50%, 89%]96%100%+0.58+0.542026-08-07 → 2026-08-30
tmin00Zbilinear365d30 1 QC2.70 [0.63, 7.01]3.39+2.08 [-0.28, 6.56]5.19 [0.77, 9.29]60% [23%, 83%]77%80%+0.32+0.232026-01-07 → 2026-08-30
tmin00Zbilinearall30 1 QC2.70 [0.65, 7.56]3.39+2.08 [-0.27, 7.24]5.19 [0.78, 9.62]60% [14%, 82%]77%80%+0.32+0.232026-01-07 → 2026-08-30
tmin00Znearest30d24 1 QC1.12 [0.89, 1.36]0.85+0.78 [0.12, 1.23]1.30 [1.12, 1.48]38% [14%, 63%]92%100%+0.36+0.482026-08-07 → 2026-08-30
tmin00Znearest90d24 1 QC1.12 [0.87, 1.38]0.85+0.78 [-0.13, 1.25]1.30 [1.09, 1.49]38% [14%, 67%]92%100%+0.36+0.482026-08-07 → 2026-08-30
tmin00Znearest365d30 1 QC3.34 [0.97, 8.10]3.65+3.07 [0.50, 7.86]5.94 [1.19, 10.56]30% [4%, 56%]73%80%+0.17+0.172026-01-07 → 2026-08-30
tmin00Znearestall30 1 QC3.34 [0.98, 8.82]3.65+3.07 [0.45, 8.60]5.94 [1.18, 10.93]30% [6%, 56%]73%80%+0.17+0.172026-01-07 → 2026-08-30
tmin12Zbilinear30d24 1 QC0.79 [0.59, 1.16]0.79-0.08 [-0.69, 0.27]1.00 [0.70, 1.49]79% [64%, 88%]96%96%+0.55+0.522026-08-07 → 2026-08-30
tmin12Zbilinear90d24 1 QC0.79 [0.57, 1.32]0.79-0.08 [-0.90, 0.30]1.00 [0.68, 1.63]79% [60%, 90%]96%96%+0.55+0.522026-08-07 → 2026-08-30
tmin12Zbilinear365d29 1 QC2.42 [0.64, 6.37]2.95+1.71 [-0.43, 5.97]4.68 [0.77, 8.63]66% [31%, 86%]79%79%+0.36+0.292026-01-07 → 2026-08-30
tmin12Zbilinearall29 1 QC2.42 [0.64, 7.07]2.95+1.71 [-0.36, 6.54]4.68 [0.76, 9.00]66% [22%, 86%]79%79%+0.36+0.292026-01-07 → 2026-08-30
tmin12Znearest30d24 1 QC1.12 [0.93, 1.35]0.86+0.75 [-0.01, 1.18]1.31 [1.11, 1.52]42% [24%, 56%]92%100%+0.36+0.472026-08-07 → 2026-08-30
tmin12Znearest90d24 1 QC1.12 [0.90, 1.35]0.86+0.75 [-0.28, 1.22]1.31 [1.05, 1.53]42% [23%, 57%]92%100%+0.36+0.472026-08-07 → 2026-08-30
tmin12Znearest365d29 1 QC2.99 [0.98, 7.40]3.21+2.69 [0.33, 7.26]5.44 [1.14, 9.94]34% [11%, 53%]76%83%+0.21+0.232026-01-07 → 2026-08-30
tmin12Znearestall29 1 QC2.99 [1.00, 8.20]3.21+2.69 [0.45, 7.99]5.44 [1.19, 10.41]34% [10%, 53%]76%83%+0.21+0.232026-01-07 → 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 6, 00Z bilinear tmax+20+100-10-202026-08-07: -5.67 °F2026-08-08: -5.12 °F2026-08-09: -6.46 °F2026-08-10: -5.84 °F2026-08-11: -5.03 °F2026-08-12: -3.35 °F2026-08-13: -1.46 °F2026-08-14: -3.39 °F2026-08-15: -3.4 °F2026-08-16: -3.1 °F2026-08-17: -5.53 °F2026-08-18: -4.45 °F2026-08-19: -3.11 °F2026-08-20: -5.82 °F2026-08-21: -6.5 °F2026-08-22: -5.91 °F2026-08-23: -12.27 °F2026-08-24: -7.88 °F2026-08-25: -6.52 °F2026-08-26: -11.19 °F2026-08-27: -4.31 °F2026-08-28: -4.73 °F2026-08-29: -8.54 °F2026-08-30: -4.41 °F2026-08-072026-08-30°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 (24 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-4.41
2026-08-29-8.54
2026-08-28-4.73
2026-08-27-4.31
2026-08-26-11.19
2026-08-25-6.52
2026-08-24-7.88
2026-08-23-12.27
2026-08-22-5.91
2026-08-21-6.50
2026-08-20-5.82
2026-08-19-3.11
2026-08-18-4.45
2026-08-17-5.53
2026-08-16-3.10
2026-08-15-3.40
2026-08-14-3.39
2026-08-13-1.46
2026-08-12-3.35
2026-08-11-5.03
2026-08-10-5.84
2026-08-09-6.46
2026-08-08-5.12
2026-08-07-5.67

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at KSAN, lead day 6-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 1 day-12 to -10 °F: 1 day-10 to -8 °F: 1 day-8 to -6 °F: 4 days-6 to -4 °F: 11 days-4 to -2 °F: 9 days-2 to 0 °F: 3 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| 4.59 · P90 |e| 7.95 °F-200+20 °Fn = 30 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
-14.00-12.001
-12.00-10.001
-10.00-8.001
-8.00-6.004
-6.00-4.0011
-4.00-2.009
-2.00+0.003
+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
2026-08245.58 -5.58
2026-0162.61 -2.61

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-07 → 2026-08-30 30
GraphCast (IFS init)2026-01-07 → 2026-08-30 30
GraphCast (IFS init)2026-01-07 → 2026-08-30 29
GraphCast (IFS init)2026-01-07 → 2026-08-30 29

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 24 +2.18 [1.24, 3.03] yes
NCEP GFS 24 +2.19 [1.47, 3.10] yes
ECMWF IFS HRES 19 +0.13 [-1.11, 1.98] no
Persistence (baseline) 24 +2.50 [1.36, 3.89] yes

Cite this page

ShortCastCheck, KSAN graphcast_ifs lead 6, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSAN/model/graphcast_ifs/lead/6/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSAN (San Diego Lindbergh), model graphcast_ifs, lead day 6. 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/6/

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