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

All stations (mean of daily station errors) · NCEP GFS · lead day 5

ALL · gfs · 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, 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
tmax00Zbilinear30d25 2 QC3.56 [3.18, 3.97]0.98-1.23 [-1.80, -0.60]4.68 [4.19, 5.16]22% [18%, 27%]39%52%+0.09+0.352026-08-06 → 2026-08-30
tmax00Zbilinear90d25 2 QC3.56 [3.12, 4.06]0.98-1.23 [-1.85, -0.32]4.68 [4.12, 5.28]22% [17%, 27%]39%52%+0.09+0.352026-08-06 → 2026-08-30
tmax00Zbilinear365d25 2 QC3.56 [3.10, 4.11]0.98-1.23 [-1.89, -0.34]4.68 [4.09, 5.32]22% [17%, 27%]39%52%+0.09+0.352026-08-06 → 2026-08-30
tmax00Zbilinearall25 2 QC3.56 [3.12, 4.07]0.98-1.23 [-1.96, -0.32]4.68 [4.10, 5.26]22% [17%, 27%]39%52%+0.09+0.352026-08-06 → 2026-08-30
tmax00Znearest30d25 2 QC3.72 [3.37, 4.14]0.97-1.15 [-1.71, -0.51]4.84 [4.37, 5.30]21% [17%, 24%]36%50%+0.05+0.352026-08-06 → 2026-08-30
tmax00Znearest90d25 2 QC3.72 [3.32, 4.23]0.97-1.15 [-1.76, -0.23]4.84 [4.34, 5.42]21% [17%, 24%]36%50%+0.05+0.352026-08-06 → 2026-08-30
tmax00Znearest365d25 2 QC3.72 [3.31, 4.28]0.97-1.15 [-1.82, -0.24]4.84 [4.34, 5.42]21% [17%, 24%]36%50%+0.05+0.352026-08-06 → 2026-08-30
tmax00Znearestall25 2 QC3.72 [3.31, 4.22]0.97-1.15 [-1.88, -0.22]4.84 [4.32, 5.42]21% [17%, 24%]36%50%+0.05+0.352026-08-06 → 2026-08-30
tmax12Zbilinear30d25 2 QC3.35 [3.09, 3.54]0.96-1.13 [-1.74, -0.34]4.51 [4.17, 4.75]26% [22%, 29%]42%56%+0.15+0.362026-08-06 → 2026-08-30
tmax12Zbilinear90d25 2 QC3.35 [3.03, 3.55]0.96-1.13 [-1.78, -0.04]4.51 [4.08, 4.76]26% [22%, 30%]42%56%+0.15+0.362026-08-06 → 2026-08-30
tmax12Zbilinear365d25 2 QC3.35 [3.03, 3.56]0.96-1.13 [-1.81, -0.06]4.51 [4.04, 4.76]26% [22%, 30%]42%56%+0.15+0.362026-08-06 → 2026-08-30
tmax12Zbilinearall25 2 QC3.35 [3.02, 3.54]0.96-1.13 [-1.87, -0.07]4.51 [4.07, 4.75]26% [22%, 30%]42%56%+0.15+0.362026-08-06 → 2026-08-30
tmax12Znearest30d25 2 QC3.57 [3.38, 3.73]0.97-1.08 [-1.69, -0.28]4.69 [4.45, 4.88]23% [19%, 27%]37%52%+0.09+0.362026-08-06 → 2026-08-30
tmax12Znearest90d25 2 QC3.57 [3.37, 3.73]0.97-1.08 [-1.74, 0.04]4.69 [4.43, 4.88]23% [19%, 27%]37%52%+0.09+0.362026-08-06 → 2026-08-30
tmax12Znearest365d25 2 QC3.57 [3.34, 3.76]0.97-1.08 [-1.77, 0.03]4.69 [4.40, 4.88]23% [19%, 27%]37%52%+0.09+0.362026-08-06 → 2026-08-30
tmax12Znearestall25 2 QC3.57 [3.35, 3.75]0.97-1.08 [-1.81, 0.01]4.69 [4.41, 4.88]23% [18%, 27%]37%52%+0.09+0.362026-08-06 → 2026-08-30
tmin00Zbilinear30d25 2 QC3.37 [3.18, 3.53]0.95+1.74 [1.20, 2.18]4.27 [4.03, 4.46]20% [17%, 22%]39%54%-0.07-0.042026-08-06 → 2026-08-30
tmin00Zbilinear90d25 2 QC3.37 [3.17, 3.57]0.95+1.74 [1.16, 2.19]4.27 [4.04, 4.50]20% [16%, 23%]39%54%-0.07-0.042026-08-06 → 2026-08-30
tmin00Zbilinear365d25 2 QC3.37 [3.14, 3.58]0.95+1.74 [1.14, 2.26]4.27 [3.98, 4.52]20% [16%, 23%]39%54%-0.07-0.042026-08-06 → 2026-08-30
tmin00Zbilinearall25 2 QC3.37 [3.15, 3.57]0.95+1.74 [1.09, 2.25]4.27 [3.98, 4.51]20% [16%, 23%]39%54%-0.07-0.042026-08-06 → 2026-08-30
tmin00Znearest30d25 2 QC3.49 [3.26, 3.66]0.96+1.85 [1.31, 2.29]4.43 [4.19, 4.62]17% [15%, 21%]37%53%-0.11-0.062026-08-06 → 2026-08-30
tmin00Znearest90d25 2 QC3.49 [3.27, 3.69]0.96+1.85 [1.29, 2.30]4.43 [4.18, 4.67]17% [14%, 21%]37%53%-0.11-0.062026-08-06 → 2026-08-30
tmin00Znearest365d25 2 QC3.49 [3.25, 3.70]0.96+1.85 [1.24, 2.37]4.43 [4.14, 4.66]17% [14%, 22%]37%53%-0.11-0.062026-08-06 → 2026-08-30
tmin00Znearestall25 2 QC3.49 [3.26, 3.70]0.96+1.85 [1.21, 2.37]4.43 [4.13, 4.65]17% [14%, 22%]37%53%-0.11-0.062026-08-06 → 2026-08-30
tmin12Zbilinear30d25 2 QC3.24 [3.09, 3.38]0.84+1.71 [1.24, 2.07]4.08 [3.91, 4.23]19% [16%, 23%]37%54%-0.03+0.082026-08-06 → 2026-08-30
tmin12Zbilinear90d25 2 QC3.24 [3.09, 3.40]0.84+1.71 [1.21, 2.10]4.08 [3.90, 4.24]19% [16%, 25%]37%54%-0.03+0.082026-08-06 → 2026-08-30
tmin12Zbilinear365d25 2 QC3.24 [3.08, 3.42]0.84+1.71 [1.21, 2.09]4.08 [3.90, 4.26]19% [15%, 24%]37%54%-0.03+0.082026-08-06 → 2026-08-30
tmin12Zbilinearall25 2 QC3.24 [3.06, 3.40]0.84+1.71 [1.17, 2.10]4.08 [3.88, 4.24]19% [15%, 24%]37%54%-0.03+0.082026-08-06 → 2026-08-30
tmin12Znearest30d25 2 QC3.39 [3.24, 3.53]0.86+1.80 [1.34, 2.16]4.25 [4.07, 4.43]18% [16%, 21%]34%52%-0.08+0.062026-08-06 → 2026-08-30
tmin12Znearest90d25 2 QC3.39 [3.24, 3.56]0.86+1.80 [1.31, 2.19]4.25 [4.05, 4.45]18% [16%, 22%]34%52%-0.08+0.062026-08-06 → 2026-08-30
tmin12Znearest365d25 2 QC3.39 [3.23, 3.56]0.86+1.80 [1.31, 2.18]4.25 [4.05, 4.47]18% [16%, 22%]34%52%-0.08+0.062026-08-06 → 2026-08-30
tmin12Znearestall25 2 QC3.39 [3.22, 3.55]0.86+1.80 [1.27, 2.18]4.25 [4.03, 4.45]18% [16%, 22%]34%52%-0.08+0.062026-08-06 → 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 NCEP GFS at ALL, lead day 5, 00Z bilinear tmax+5+2.50-2.5-52026-08-06: -0.68 °F2026-08-07: +0.55 °F2026-08-08: -0.73 °F2026-08-09: -0.26 °F2026-08-10: -0.28 °F2026-08-11: +0.29 °F2026-08-12: -1.35 °F2026-08-13: -0.88 °F2026-08-14: -2.95 °F2026-08-15: -1.33 °F2026-08-16: +0.27 °F2026-08-17: -0.45 °F2026-08-18: -1.59 °F2026-08-19: -1.09 °F2026-08-20: -0.7 °F2026-08-21: -4.33 °F2026-08-22: -1.53 °F2026-08-23: -2.72 °F2026-08-24: -1.59 °F2026-08-25: -1.93 °F2026-08-26: -1.45 °F2026-08-27: -2.62 °F2026-08-28: -3.59 °F2026-08-29: +0.65 °F2026-08-30: -0.49 °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
2026-08-30-0.49
2026-08-29+0.65
2026-08-28-3.59
2026-08-27-2.62
2026-08-26-1.45
2026-08-25-1.93
2026-08-24-1.59
2026-08-23-2.72
2026-08-22-1.53
2026-08-21-4.33
2026-08-20-0.70
2026-08-19-1.09
2026-08-18-1.59
2026-08-17-0.45
2026-08-16+0.27
2026-08-15-1.33
2026-08-14-2.95
2026-08-13-0.88
2026-08-12-1.35
2026-08-11+0.29
2026-08-10-0.28
2026-08-09-0.26
2026-08-08-0.73
2026-08-07+0.55
2026-08-06-0.68

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at ALL, lead day 5-5 to -4.5 °F: 0 days-4.5 to -4 °F: 1 day-4 to -3.5 °F: 1 day-3.5 to -3 °F: 0 days-3 to -2.5 °F: 3 days-2.5 to -2 °F: 0 days-2 to -1.5 °F: 4 days-1.5 to -1 °F: 4 days-1 to -0.5 °F: 4 days-0.5 to 0 °F: 4 days0 to 0.5 °F: 2 days0.5 to 1 °F: 2 days1 to 1.5 °F: 0 days1.5 to 2 °F: 0 days2 to 2.5 °F: 0 days2.5 to 3 °F: 0 days3 to 3.5 °F: 0 days3.5 to 4 °F: 0 days4 to 4.5 °F: 0 days4.5 to 5 °F: 0 daysdashed: P50 |e| 1.09 · P90 |e| 2.86 °F-50+5 °Fn = 25 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
-5.00-4.500
-4.50-4.001
-4.00-3.501
-3.50-3.000
-3.00-2.503
-2.50-2.000
-2.00-1.504
-1.50-1.004
-1.00-0.504
-0.50+0.004
+0.00+0.502
+0.50+1.002
+1.00+1.500
+1.50+2.000
+2.00+2.500
+2.50+3.000
+3.00+3.500
+3.50+4.000
+4.00+4.500
+4.50+5.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08251.37 -1.23

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25

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 25 -0.35 [-0.86, 0.16] no
GraphCast (IFS init) 25 -1.85 [-2.28, -1.50] yes
ECMWF IFS HRES 18 -0.02 [-0.81, 0.59] no
Persistence (baseline) 25 -0.37 [-1.18, 0.48] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: ALL (All stations (mean of daily station errors)), model gfs, 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/ALL/model/gfs/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