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 · NCEP GFS · lead day 6

KSAN · gfs · 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, gfs-0p25, starting 2026-08-01 — 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 QC3.40 [2.24, 4.75]1.84-3.35 [-4.73, -2.20]4.21 [2.69, 5.71]12% [0%, 23%]33%46%-0.10+0.372026-08-07 → 2026-08-30
tmax00Zbilinear90d24 1 QC3.40 [2.22, 4.94]1.84-3.35 [-4.94, -2.16]4.21 [2.64, 5.79]12% [0%, 24%]33%46%-0.10+0.372026-08-07 → 2026-08-30
tmax00Zbilinear365d24 1 QC3.40 [2.13, 5.09]1.84-3.35 [-5.02, -2.10]4.21 [2.56, 6.03]12% [0%, 25%]33%46%-0.10+0.372026-08-07 → 2026-08-30
tmax00Zbilinearall24 1 QC3.40 [2.20, 5.09]1.84-3.35 [-5.02, -2.13]4.21 [2.58, 6.01]12% [0%, 25%]33%46%-0.10+0.372026-08-07 → 2026-08-30
tmax00Znearest30d24 1 QC5.68 [4.19, 7.40]1.99-5.68 [-7.40, -4.19]6.28 [4.46, 8.01]0% [0%, 0%]0%12%-0.84+0.322026-08-07 → 2026-08-30
tmax00Znearest90d24 1 QC5.68 [4.19, 7.58]1.99-5.68 [-7.58, -4.19]6.28 [4.41, 8.17]0% [0%, 0%]0%12%-0.84+0.322026-08-07 → 2026-08-30
tmax00Znearest365d24 1 QC5.68 [4.09, 7.76]1.99-5.68 [-7.76, -4.09]6.28 [4.31, 8.40]0% [0%, 0%]0%12%-0.84+0.322026-08-07 → 2026-08-30
tmax00Znearestall24 1 QC5.68 [4.15, 7.73]1.99-5.68 [-7.73, -4.15]6.28 [4.33, 8.38]0% [0%, 0%]0%12%-0.84+0.322026-08-07 → 2026-08-30
tmax12Zbilinear30d24 1 QC3.50 [2.50, 4.52]1.53-3.50 [-4.52, -2.50]4.06 [2.87, 5.10]8% [0%, 20%]25%50%-0.14+0.482026-08-07 → 2026-08-30
tmax12Zbilinear90d24 1 QC3.50 [2.45, 4.60]1.53-3.50 [-4.60, -2.45]4.06 [2.76, 5.16]8% [0%, 21%]25%50%-0.14+0.482026-08-07 → 2026-08-30
tmax12Zbilinear365d24 1 QC3.50 [2.40, 4.69]1.53-3.50 [-4.69, -2.40]4.06 [2.69, 5.29]8% [0%, 23%]25%50%-0.14+0.482026-08-07 → 2026-08-30
tmax12Zbilinearall24 1 QC3.50 [2.46, 4.69]1.53-3.50 [-4.69, -2.46]4.06 [2.77, 5.29]8% [0%, 21%]25%50%-0.14+0.482026-08-07 → 2026-08-30
tmax12Znearest30d24 1 QC5.87 [4.63, 7.24]1.62-5.87 [-7.24, -4.63]6.26 [4.78, 7.62]0% [0%, 0%]0%4%-0.90+0.442026-08-07 → 2026-08-30
tmax12Znearest90d24 1 QC5.87 [4.60, 7.37]1.62-5.87 [-7.37, -4.60]6.26 [4.74, 7.77]0% [0%, 0%]0%4%-0.90+0.442026-08-07 → 2026-08-30
tmax12Znearest365d24 1 QC5.87 [4.43, 7.51]1.62-5.87 [-7.51, -4.43]6.26 [4.54, 7.90]0% [0%, 0%]0%4%-0.90+0.442026-08-07 → 2026-08-30
tmax12Znearestall24 1 QC5.87 [4.50, 7.45]1.62-5.87 [-7.45, -4.50]6.26 [4.64, 7.87]0% [0%, 0%]0%4%-0.90+0.442026-08-07 → 2026-08-30
tmin00Zbilinear30d24 1 QC2.35 [1.51, 3.15]1.14+2.31 [1.38, 3.15]2.81 [1.84, 3.62]21% [7%, 42%]38%75%-0.34+0.302026-08-07 → 2026-08-30
tmin00Zbilinear90d24 1 QC2.35 [1.45, 3.28]1.14+2.31 [1.27, 3.25]2.81 [1.80, 3.72]21% [7%, 46%]38%75%-0.34+0.302026-08-07 → 2026-08-30
tmin00Zbilinear365d24 1 QC2.35 [1.47, 3.41]1.14+2.31 [1.35, 3.35]2.81 [1.78, 3.83]21% [5%, 46%]38%75%-0.34+0.302026-08-07 → 2026-08-30
tmin00Zbilinearall24 1 QC2.35 [1.43, 3.37]1.14+2.31 [1.26, 3.36]2.81 [1.79, 3.83]21% [7%, 50%]38%75%-0.34+0.302026-08-07 → 2026-08-30
tmin00Znearest30d24 1 QC1.83 [1.27, 2.44]1.11+1.55 [0.63, 2.29]2.16 [1.42, 2.76]25% [7%, 48%]62%92%-0.05+0.312026-08-07 → 2026-08-30
tmin00Znearest90d24 1 QC1.83 [1.21, 2.48]1.11+1.55 [0.41, 2.36]2.16 [1.33, 2.83]25% [5%, 55%]62%92%-0.05+0.312026-08-07 → 2026-08-30
tmin00Znearest365d24 1 QC1.83 [1.21, 2.57]1.11+1.55 [0.45, 2.44]2.16 [1.33, 2.89]25% [0%, 54%]62%92%-0.05+0.312026-08-07 → 2026-08-30
tmin00Znearestall24 1 QC1.83 [1.18, 2.53]1.11+1.55 [0.27, 2.35]2.16 [1.26, 2.86]25% [0%, 53%]62%92%-0.05+0.312026-08-07 → 2026-08-30
tmin12Zbilinear30d24 1 QC2.38 [1.53, 3.18]1.30+2.19 [1.25, 3.09]2.76 [1.83, 3.49]17% [0%, 38%]38%71%-0.36+0.202026-08-07 → 2026-08-30
tmin12Zbilinear90d24 1 QC2.38 [1.39, 3.25]1.30+2.19 [1.16, 3.14]2.76 [1.64, 3.55]17% [0%, 40%]38%71%-0.36+0.202026-08-07 → 2026-08-30
tmin12Zbilinear365d24 1 QC2.38 [1.43, 3.39]1.30+2.19 [1.25, 3.34]2.76 [1.65, 3.68]17% [0%, 40%]38%71%-0.36+0.202026-08-07 → 2026-08-30
tmin12Zbilinearall24 1 QC2.38 [1.42, 3.42]1.30+2.19 [1.12, 3.34]2.76 [1.64, 3.67]17% [0%, 43%]38%71%-0.36+0.202026-08-07 → 2026-08-30
tmin12Znearest30d24 1 QC1.75 [1.26, 2.29]1.16+1.46 [0.72, 2.17]2.05 [1.50, 2.55]25% [10%, 42%]54%92%-0.00+0.282026-08-07 → 2026-08-30
tmin12Znearest90d24 1 QC1.75 [1.22, 2.34]1.16+1.46 [0.58, 2.24]2.05 [1.42, 2.57]25% [7%, 43%]54%92%-0.00+0.282026-08-07 → 2026-08-30
tmin12Znearest365d24 1 QC1.75 [1.23, 2.43]1.16+1.46 [0.57, 2.34]2.05 [1.44, 2.67]25% [0%, 43%]54%92%-0.00+0.282026-08-07 → 2026-08-30
tmin12Znearestall24 1 QC1.75 [1.22, 2.42]1.16+1.46 [0.45, 2.31]2.05 [1.43, 2.66]25% [0%, 44%]54%92%-0.00+0.282026-08-07 → 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 NCEP GFS at KSAN, lead day 6, 00Z bilinear tmax+20+100-10-202026-08-07: -5.1 °F2026-08-08: -3.07 °F2026-08-09: -4.87 °F2026-08-10: -3.96 °F2026-08-11: -2.82 °F2026-08-12: -1.14 °F2026-08-13: -0.36 °F2026-08-14: -1.75 °F2026-08-15: -4.31 °F2026-08-16: -1.6 °F2026-08-17: -2.94 °F2026-08-18: -0.4 °F2026-08-19: -1.37 °F2026-08-20: -3.7 °F2026-08-21: +0.53 °F2026-08-22: -3.13 °F2026-08-23: -5.95 °F2026-08-24: -3.37 °F2026-08-25: -7.07 °F2026-08-26: -11.85 °F2026-08-27: -4.3 °F2026-08-28: -1.44 °F2026-08-29: -4.45 °F2026-08-30: -2.03 °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
2026-08-30-2.03
2026-08-29-4.45
2026-08-28-1.44
2026-08-27-4.30
2026-08-26-11.85
2026-08-25-7.07
2026-08-24-3.37
2026-08-23-5.95
2026-08-22-3.13
2026-08-21+0.53
2026-08-20-3.70
2026-08-19-1.37
2026-08-18-0.40
2026-08-17-2.94
2026-08-16-1.60
2026-08-15-4.31
2026-08-14-1.75
2026-08-13-0.36
2026-08-12-1.14
2026-08-11-2.82
2026-08-10-3.96
2026-08-09-4.87
2026-08-08-3.07
2026-08-07-5.10

Error distribution

Distribution of the signed daily error in °F for NCEP GFS 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: 0 days-12 to -10 °F: 1 day-10 to -8 °F: 0 days-8 to -6 °F: 1 day-6 to -4 °F: 6 days-4 to -2 °F: 8 days-2 to 0 °F: 7 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| 3.1 · P90 |e| 5.69 °F-200+20 °Fn = 24 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
-10.00-8.000
-8.00-6.001
-6.00-4.006
-4.00-2.008
-2.00+0.007
+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
2026-08243.40 -3.35

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-07 → 2026-08-30 24
NCEP GFS2026-08-07 → 2026-08-30 24
NCEP GFS2026-08-07 → 2026-08-30 24
NCEP GFS2026-08-07 → 2026-08-30 24

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means NCEP GFS has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 24 -0.01 [-0.82, 1.06] no
GraphCast (IFS init) 24 -2.19 [-3.10, -1.47] yes
ECMWF IFS HRES 19 -2.10 [-3.96, 0.27] no
Persistence (baseline) 24 +0.31 [-0.68, 1.95] no

Cite this page

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

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