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 8

KSAN · gfs · 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, 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
tmax00Zbilinear30d22 1 QC3.83 [2.65, 5.14]2.22-3.55 [-5.04, -2.08]4.61 [3.25, 6.02]9% [0%, 21%]27%45%-0.05+0.322026-08-09 → 2026-08-30
tmax00Zbilinear90d22 1 QC3.83 [2.65, 5.26]2.22-3.55 [-5.15, -2.05]4.61 [3.18, 6.14]9% [0%, 25%]27%45%-0.05+0.322026-08-09 → 2026-08-30
tmax00Zbilinear365d22 1 QC3.83 [2.65, 5.29]2.22-3.55 [-5.25, -1.97]4.61 [3.11, 6.11]9% [0%, 25%]27%45%-0.05+0.322026-08-09 → 2026-08-30
tmax00Zbilinearall22 1 QC3.83 [2.38, 5.29]2.22-3.55 [-5.18, -1.65]4.61 [2.95, 6.07]9% [0%, 30%]27%45%-0.05+0.322026-08-09 → 2026-08-30
tmax00Znearest30d22 1 QC5.82 [4.16, 7.61]2.19-5.82 [-7.61, -4.16]6.50 [4.74, 8.16]0% [0%, 0%]9%18%-0.60+0.332026-08-09 → 2026-08-30
tmax00Znearest90d22 1 QC5.82 [4.14, 7.80]2.19-5.82 [-7.80, -4.14]6.50 [4.69, 8.27]0% [0%, 0%]9%18%-0.60+0.332026-08-09 → 2026-08-30
tmax00Znearest365d22 1 QC5.82 [4.06, 7.84]2.19-5.82 [-7.84, -4.06]6.50 [4.60, 8.31]0% [0%, 0%]9%18%-0.60+0.332026-08-09 → 2026-08-30
tmax00Znearestall22 1 QC5.82 [3.85, 7.72]2.19-5.82 [-7.72, -3.85]6.50 [4.28, 8.29]0% [0%, 0%]9%18%-0.60+0.332026-08-09 → 2026-08-30
tmax12Zbilinear30d22 1 QC3.82 [2.52, 5.32]2.25-3.55 [-5.02, -2.34]4.60 [3.06, 6.03]9% [0%, 23%]23%41%-0.05+0.322026-08-09 → 2026-08-30
tmax12Zbilinear90d22 1 QC3.82 [2.42, 5.47]2.25-3.55 [-5.16, -2.24]4.60 [2.97, 6.19]9% [0%, 23%]23%41%-0.05+0.322026-08-09 → 2026-08-30
tmax12Zbilinear365d22 1 QC3.82 [2.44, 5.56]2.25-3.55 [-5.15, -2.26]4.60 [3.00, 6.25]9% [0%, 24%]23%41%-0.05+0.322026-08-09 → 2026-08-30
tmax12Zbilinearall22 1 QC3.82 [2.14, 5.48]2.25-3.55 [-5.08, -2.04]4.60 [2.74, 6.18]9% [0%, 25%]23%41%-0.05+0.322026-08-09 → 2026-08-30
tmax12Znearest30d22 1 QC5.89 [4.23, 7.82]2.43-5.89 [-7.82, -4.23]6.66 [4.67, 8.56]0% [0%, 0%]14%23%-0.62+0.262026-08-09 → 2026-08-30
tmax12Znearest90d22 1 QC5.89 [4.14, 8.08]2.43-5.89 [-8.08, -4.14]6.66 [4.54, 8.77]0% [0%, 0%]14%23%-0.62+0.262026-08-09 → 2026-08-30
tmax12Znearest365d22 1 QC5.89 [4.11, 8.12]2.43-5.89 [-8.12, -4.11]6.66 [4.56, 8.87]0% [0%, 0%]14%23%-0.62+0.262026-08-09 → 2026-08-30
tmax12Znearestall22 1 QC5.89 [3.86, 8.03]2.43-5.89 [-8.03, -3.86]6.66 [4.23, 8.80]0% [0%, 0%]14%23%-0.62+0.262026-08-09 → 2026-08-30
tmin00Zbilinear30d22 1 QC2.08 [1.45, 2.67]1.56+1.70 [0.45, 2.50]2.79 [1.76, 3.66]36% [23%, 50%]55%77%-0.20+0.062026-08-09 → 2026-08-30
tmin00Zbilinear90d22 1 QC2.08 [1.41, 2.71]1.56+1.70 [0.24, 2.60]2.79 [1.65, 3.70]36% [21%, 50%]55%77%-0.20+0.062026-08-09 → 2026-08-30
tmin00Zbilinear365d22 1 QC2.08 [1.40, 2.76]1.56+1.70 [0.25, 2.67]2.79 [1.66, 3.80]36% [21%, 50%]55%77%-0.20+0.062026-08-09 → 2026-08-30
tmin00Zbilinearall22 1 QC2.08 [1.40, 2.77]1.56+1.70 [0.27, 2.65]2.79 [1.63, 3.81]36% [20%, 50%]55%77%-0.20+0.062026-08-09 → 2026-08-30
tmin00Znearest30d22 1 QC1.67 [1.12, 2.14]1.50+1.05 [-0.21, 1.85]2.28 [1.46, 2.87]36% [21%, 54%]68%86%+0.03+0.092026-08-09 → 2026-08-30
tmin00Znearest90d22 1 QC1.67 [1.03, 2.16]1.50+1.05 [-0.46, 1.88]2.28 [1.33, 2.93]36% [20%, 57%]68%86%+0.03+0.092026-08-09 → 2026-08-30
tmin00Znearest365d22 1 QC1.67 [1.00, 2.21]1.50+1.05 [-0.42, 1.95]2.28 [1.31, 3.00]36% [19%, 57%]68%86%+0.03+0.092026-08-09 → 2026-08-30
tmin00Znearestall22 1 QC1.67 [0.92, 2.21]1.50+1.05 [-0.42, 1.90]2.28 [1.17, 3.00]36% [15%, 62%]68%86%+0.03+0.092026-08-09 → 2026-08-30
tmin12Zbilinear30d22 1 QC2.09 [1.23, 2.89]1.55+1.91 [1.07, 2.62]2.81 [1.60, 3.73]32% [19%, 50%]59%77%-0.21+0.062026-08-09 → 2026-08-30
tmin12Zbilinear90d22 1 QC2.09 [1.07, 2.95]1.55+1.91 [0.98, 2.67]2.81 [1.40, 3.75]32% [19%, 51%]59%77%-0.21+0.062026-08-09 → 2026-08-30
tmin12Zbilinear365d22 1 QC2.09 [1.12, 3.06]1.55+1.91 [1.05, 2.73]2.81 [1.41, 3.96]32% [18%, 50%]59%77%-0.21+0.062026-08-09 → 2026-08-30
tmin12Zbilinearall22 1 QC2.09 [1.10, 3.06]1.55+1.91 [1.04, 2.76]2.81 [1.43, 4.02]32% [14%, 50%]59%77%-0.21+0.062026-08-09 → 2026-08-30
tmin12Znearest30d22 1 QC1.77 [1.07, 2.41]1.50+1.17 [0.19, 1.92]2.30 [1.28, 3.04]41% [19%, 65%]68%86%-0.02+0.092026-08-09 → 2026-08-30
tmin12Znearest90d22 1 QC1.77 [0.91, 2.47]1.50+1.17 [-0.12, 1.97]2.30 [1.11, 3.07]41% [15%, 71%]68%86%-0.02+0.092026-08-09 → 2026-08-30
tmin12Znearest365d22 1 QC1.77 [0.90, 2.61]1.50+1.17 [-0.08, 1.99]2.30 [1.12, 3.28]41% [14%, 71%]68%86%-0.02+0.092026-08-09 → 2026-08-30
tmin12Znearestall22 1 QC1.77 [0.97, 2.62]1.50+1.17 [-0.09, 1.94]2.30 [1.15, 3.29]41% [14%, 71%]68%86%-0.02+0.092026-08-09 → 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 NCEP GFS at KSAN, lead day 8, 00Z bilinear tmax+20+100-10-202026-08-09: -9.47 °F2026-08-10: -4.5 °F2026-08-11: -4.92 °F2026-08-12: -2.03 °F2026-08-13: -1.06 °F2026-08-14: -1.12 °F2026-08-15: +0.91 °F2026-08-16: +1.68 °F2026-08-17: -2.98 °F2026-08-18: -4.5 °F2026-08-19: -3.36 °F2026-08-20: -4.26 °F2026-08-21: -5.89 °F2026-08-22: -2.87 °F2026-08-23: -1.88 °F2026-08-24: -2.78 °F2026-08-25: -3.52 °F2026-08-26: -10.7 °F2026-08-27: -3.15 °F2026-08-28: -6.04 °F2026-08-29: -6.1 °F2026-08-30: +0.47 °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+0.47
2026-08-29-6.10
2026-08-28-6.04
2026-08-27-3.15
2026-08-26-10.70
2026-08-25-3.52
2026-08-24-2.78
2026-08-23-1.88
2026-08-22-2.87
2026-08-21-5.89
2026-08-20-4.26
2026-08-19-3.36
2026-08-18-4.50
2026-08-17-2.98
2026-08-16+1.68
2026-08-15+0.91
2026-08-14-1.12
2026-08-13-1.06
2026-08-12-2.03
2026-08-11-4.92
2026-08-10-4.50
2026-08-09-9.47

Error distribution

Distribution of the signed daily error in °F for NCEP GFS 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: 0 days-12 to -10 °F: 1 day-10 to -8 °F: 1 day-8 to -6 °F: 2 days-6 to -4 °F: 5 days-4 to -2 °F: 7 days-2 to 0 °F: 3 days0 to 2 °F: 3 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| 3.26 · P90 |e| 6.1 °F-200+20 °Fn = 22 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
-8.00-6.002
-6.00-4.005
-4.00-2.007
-2.00+0.003
+0.00+2.003
+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
2026-08223.83 -3.55

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 2026-08-30 22
NCEP GFS2026-08-09 → 2026-08-30 22

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 22 +0.25 [-0.75, 1.65] no
GraphCast (IFS init) 22 -2.09 [-3.84, -0.51] yes
ECMWF IFS HRES 17 -2.13 [-4.20, 1.32] no
Persistence (baseline) 22 +0.19 [-0.90, 2.55] no

Cite this page

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

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