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

Los Angeles Intl · NCEP GFS · lead day 4

KLAX · gfs · lead 4

Target day = initialization date + 4 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, 2 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
tmax00Zbilinear30d26 2 QC2.18 [1.56, 3.02]2.19-0.18 [-1.52, 1.03]2.80 [1.98, 3.59]35% [14%, 50%]58%73%+0.13+0.072026-08-05 → 2026-08-30
tmax00Zbilinear90d26 2 QC2.18 [1.55, 3.13]2.19-0.18 [-1.80, 1.36]2.80 [1.90, 3.71]35% [9%, 50%]58%73%+0.13+0.072026-08-05 → 2026-08-30
tmax00Zbilinear365d26 2 QC2.18 [1.54, 3.39]2.19-0.18 [-2.17, 1.39]2.80 [1.89, 3.91]35% [8%, 52%]58%73%+0.13+0.072026-08-05 → 2026-08-30
tmax00Zbilinearall26 2 QC2.18 [1.53, 3.28]2.19-0.18 [-1.91, 1.31]2.80 [1.88, 3.74]35% [8%, 52%]58%73%+0.13+0.072026-08-05 → 2026-08-30
tmax00Znearest30d26 2 QC2.44 [1.61, 3.47]2.30-0.70 [-1.89, 0.40]3.24 [2.02, 4.31]27% [18%, 35%]54%69%+0.02+0.032026-08-05 → 2026-08-30
tmax00Znearest90d26 2 QC2.44 [1.50, 3.54]2.30-0.70 [-2.13, 0.63]3.24 [1.84, 4.40]27% [18%, 36%]54%69%+0.02+0.032026-08-05 → 2026-08-30
tmax00Znearest365d26 2 QC2.44 [1.52, 3.82]2.30-0.70 [-2.37, 0.73]3.24 [1.85, 4.58]27% [15%, 36%]54%69%+0.02+0.032026-08-05 → 2026-08-30
tmax00Znearestall26 2 QC2.44 [1.49, 3.67]2.30-0.70 [-2.23, 0.77]3.24 [1.83, 4.55]27% [15%, 35%]54%69%+0.02+0.032026-08-05 → 2026-08-30
tmax12Zbilinear30d26 2 QC2.13 [1.42, 2.90]2.09-0.68 [-1.98, 0.47]2.75 [1.86, 3.52]35% [17%, 52%]62%77%+0.15+0.112026-08-05 → 2026-08-30
tmax12Zbilinear90d26 2 QC2.13 [1.28, 2.96]2.09-0.68 [-2.21, 0.80]2.75 [1.65, 3.57]35% [14%, 56%]62%77%+0.15+0.112026-08-05 → 2026-08-30
tmax12Zbilinear365d26 2 QC2.13 [1.31, 3.20]2.09-0.68 [-2.43, 0.80]2.75 [1.75, 3.76]35% [11%, 54%]62%77%+0.15+0.112026-08-05 → 2026-08-30
tmax12Zbilinearall26 2 QC2.13 [1.25, 3.12]2.09-0.68 [-2.33, 0.71]2.75 [1.66, 3.66]35% [12%, 56%]62%77%+0.15+0.112026-08-05 → 2026-08-30
tmax12Znearest30d26 2 QC2.56 [1.60, 3.56]2.27-1.41 [-2.59, -0.30]3.21 [2.11, 4.13]31% [14%, 48%]46%58%-0.02+0.042026-08-05 → 2026-08-30
tmax12Znearest90d26 2 QC2.56 [1.41, 3.64]2.27-1.41 [-2.87, -0.11]3.21 [1.79, 4.17]31% [11%, 50%]46%58%-0.02+0.042026-08-05 → 2026-08-30
tmax12Znearest365d26 2 QC2.56 [1.46, 4.03]2.27-1.41 [-2.97, -0.03]3.21 [1.92, 4.40]31% [7%, 50%]46%58%-0.02+0.042026-08-05 → 2026-08-30
tmax12Znearestall26 2 QC2.56 [1.44, 3.83]2.27-1.41 [-2.94, -0.09]3.21 [1.84, 4.34]31% [7%, 50%]46%58%-0.02+0.042026-08-05 → 2026-08-30
tmin00Zbilinear30d26 2 QC3.61 [2.57, 4.68]1.65+3.54 [2.40, 4.68]4.07 [3.07, 4.94]15% [0%, 33%]19%38%-1.35-0.182026-08-05 → 2026-08-30
tmin00Zbilinear90d26 2 QC3.61 [2.44, 4.79]1.65+3.54 [2.30, 4.79]4.07 [2.95, 5.04]15% [0%, 33%]19%38%-1.35-0.182026-08-05 → 2026-08-30
tmin00Zbilinear365d26 2 QC3.61 [2.33, 4.92]1.65+3.54 [2.15, 4.92]4.07 [2.78, 5.10]15% [0%, 33%]19%38%-1.35-0.182026-08-05 → 2026-08-30
tmin00Zbilinearall26 2 QC3.61 [2.31, 4.91]1.65+3.54 [2.12, 4.91]4.07 [2.81, 5.09]15% [0%, 33%]19%38%-1.35-0.182026-08-05 → 2026-08-30
tmin00Znearest30d26 2 QC2.58 [1.75, 3.46]1.78+2.03 [0.80, 3.26]2.98 [1.98, 3.79]12% [0%, 29%]42%62%-0.68-0.272026-08-05 → 2026-08-30
tmin00Znearest90d26 2 QC2.58 [1.66, 3.51]1.78+2.03 [0.68, 3.37]2.98 [1.87, 3.85]12% [0%, 33%]42%62%-0.68-0.272026-08-05 → 2026-08-30
tmin00Znearest365d26 2 QC2.58 [1.58, 3.61]1.78+2.03 [0.50, 3.54]2.98 [1.75, 3.89]12% [0%, 35%]42%62%-0.68-0.272026-08-05 → 2026-08-30
tmin00Znearestall26 2 QC2.58 [1.67, 3.56]1.78+2.03 [0.53, 3.50]2.98 [1.87, 3.87]12% [0%, 35%]42%62%-0.68-0.272026-08-05 → 2026-08-30
tmin12Zbilinear30d26 2 QC3.49 [2.58, 4.39]1.47+3.38 [2.33, 4.39]3.86 [3.02, 4.58]15% [0%, 33%]19%35%-1.27-0.052026-08-05 → 2026-08-30
tmin12Zbilinear90d26 2 QC3.49 [2.50, 4.45]1.47+3.38 [2.28, 4.45]3.86 [2.92, 4.62]15% [0%, 33%]19%35%-1.27-0.052026-08-05 → 2026-08-30
tmin12Zbilinear365d26 2 QC3.49 [2.36, 4.55]1.47+3.38 [2.14, 4.55]3.86 [2.76, 4.68]15% [0%, 33%]19%35%-1.27-0.052026-08-05 → 2026-08-30
tmin12Zbilinearall26 2 QC3.49 [2.36, 4.57]1.47+3.38 [2.07, 4.57]3.86 [2.79, 4.68]15% [0%, 33%]19%35%-1.27-0.052026-08-05 → 2026-08-30
tmin12Znearest30d26 2 QC2.40 [1.70, 3.12]1.65+1.85 [0.66, 2.99]2.70 [1.98, 3.31]23% [7%, 42%]35%62%-0.56-0.182026-08-05 → 2026-08-30
tmin12Znearest90d26 2 QC2.40 [1.60, 3.17]1.65+1.85 [0.54, 3.06]2.70 [1.85, 3.36]23% [0%, 46%]35%62%-0.56-0.182026-08-05 → 2026-08-30
tmin12Znearest365d26 2 QC2.40 [1.59, 3.24]1.65+1.85 [0.34, 3.19]2.70 [1.82, 3.38]23% [0%, 46%]35%62%-0.56-0.182026-08-05 → 2026-08-30
tmin12Znearestall26 2 QC2.40 [1.58, 3.21]1.65+1.85 [0.39, 3.17]2.70 [1.85, 3.39]23% [0%, 48%]35%62%-0.56-0.182026-08-05 → 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 KLAX, lead day 4, 00Z bilinear tmax+10+50-5-102026-08-05: +2.39 °F2026-08-06: +1.93 °F2026-08-07: +0.37 °F2026-08-08: +1.53 °F2026-08-09: +2.44 °F2026-08-10: +1.63 °F2026-08-11: +0.56 °F2026-08-12: -0.28 °F2026-08-13: -3.17 °F2026-08-14: -4.02 °F2026-08-15: -0.47 °F2026-08-16: +0.48 °F2026-08-17: +2.82 °F2026-08-18: +0.31 °F2026-08-19: +0.09 °F2026-08-20: +5.11 °F2026-08-21: -1.45 °F2026-08-22: +0.7 °F2026-08-23: -1.67 °F2026-08-24: -0.97 °F2026-08-25: +5.68 °F2026-08-26: -2.53 °F2026-08-27: -6.45 °F2026-08-28: -1.53 °F2026-08-29: -4.7 °F2026-08-30: -3.36 °F2026-08-052026-08-30°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 (26 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-3.36
2026-08-29-4.70
2026-08-28-1.53
2026-08-27-6.45
2026-08-26-2.53
2026-08-25+5.68
2026-08-24-0.97
2026-08-23-1.67
2026-08-22+0.70
2026-08-21-1.45
2026-08-20+5.11
2026-08-19+0.09
2026-08-18+0.31
2026-08-17+2.82
2026-08-16+0.48
2026-08-15-0.47
2026-08-14-4.02
2026-08-13-3.17
2026-08-12-0.28
2026-08-11+0.56
2026-08-10+1.63
2026-08-09+2.44
2026-08-08+1.53
2026-08-07+0.37
2026-08-06+1.93
2026-08-05+2.39

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KLAX, lead day 4-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 1 day-6 to -5 °F: 0 days-5 to -4 °F: 2 days-4 to -3 °F: 2 days-3 to -2 °F: 1 day-2 to -1 °F: 3 days-1 to 0 °F: 3 days0 to 1 °F: 6 days1 to 2 °F: 3 days2 to 3 °F: 3 days3 to 4 °F: 0 days4 to 5 °F: 0 days5 to 6 °F: 2 days6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 1.65 · P90 |e| 4.9 °F-100+10 °Fn = 26 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
-10.00-9.000
-9.00-8.000
-8.00-7.000
-7.00-6.001
-6.00-5.000
-5.00-4.002
-4.00-3.002
-3.00-2.001
-2.00-1.003
-1.00+0.003
+0.00+1.006
+1.00+2.003
+2.00+3.003
+3.00+4.000
+4.00+5.000
+5.00+6.002
+6.00+7.000
+7.00+8.000
+8.00+9.000
+9.00+10.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08262.18 -0.18

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-05 → 2026-08-30 26
NCEP GFS2026-08-05 → 2026-08-30 26
NCEP GFS2026-08-05 → 2026-08-30 26
NCEP GFS2026-08-05 → 2026-08-30 26

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 26 +0.56 [-0.35, 1.64] no
GraphCast (IFS init) 25 -1.60 [-2.26, -1.00] yes
ECMWF IFS HRES 20 +0.44 [-0.56, 1.81] no
Persistence (baseline) 26 -0.32 [-1.00, 0.29] no

Cite this page

ShortCastCheck, KLAX gfs lead 4, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KLAX/model/gfs/lead/4/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KLAX (Los Angeles Intl), model gfs, lead day 4. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KLAX/model/gfs/lead/4/

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