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

Washington Reagan · NCEP GFS · lead day 1

KDCA · gfs · lead 1

Target day = initialization date + 1 day. 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
tmax00Zbilinear30d29 1 QC3.74 [2.75, 4.76]3.42-2.71 [-4.29, -1.09]4.94 [3.59, 6.04]24% [10%, 41%]41%45%-0.04+0.052026-08-02 → 2026-08-30
tmax00Zbilinear90d29 1 QC3.74 [2.57, 4.96]3.42-2.71 [-4.49, -0.81]4.94 [3.22, 6.12]24% [5%, 42%]41%45%-0.04+0.052026-08-02 → 2026-08-30
tmax00Zbilinear365d29 1 QC3.74 [2.42, 5.10]3.42-2.71 [-4.75, -0.74]4.94 [2.97, 6.29]24% [5%, 44%]41%45%-0.04+0.052026-08-02 → 2026-08-30
tmax00Zbilinearall29 1 QC3.74 [2.47, 4.97]3.42-2.71 [-4.71, -0.83]4.94 [3.28, 6.27]24% [5%, 43%]41%45%-0.04+0.052026-08-02 → 2026-08-30
tmax00Znearest30d29 1 QC3.77 [2.72, 4.81]3.53-2.63 [-4.34, -0.87]4.99 [3.62, 6.16]24% [14%, 37%]41%52%-0.05+0.022026-08-02 → 2026-08-30
tmax00Znearest90d29 1 QC3.77 [2.55, 5.02]3.53-2.63 [-4.55, -0.58]4.99 [3.27, 6.24]24% [11%, 36%]41%52%-0.05+0.022026-08-02 → 2026-08-30
tmax00Znearest365d29 1 QC3.77 [2.39, 5.16]3.53-2.63 [-4.77, -0.60]4.99 [2.96, 6.40]24% [12%, 38%]41%52%-0.05+0.022026-08-02 → 2026-08-30
tmax00Znearestall29 1 QC3.77 [2.50, 5.01]3.53-2.63 [-4.67, -0.58]4.99 [3.25, 6.27]24% [10%, 36%]41%52%-0.05+0.022026-08-02 → 2026-08-30
tmax12Zbilinear30d29 1 QC2.62 [2.06, 3.18]2.68-1.00 [-2.22, 0.26]3.41 [2.77, 3.97]31% [18%, 43%]52%59%+0.27+0.252026-08-02 → 2026-08-30
tmax12Zbilinear90d29 1 QC2.62 [1.98, 3.30]2.68-1.00 [-2.26, 0.44]3.41 [2.64, 4.07]31% [14%, 44%]52%59%+0.27+0.252026-08-02 → 2026-08-30
tmax12Zbilinear365d29 1 QC2.62 [1.90, 3.34]2.68-1.00 [-2.46, 0.44]3.41 [2.55, 4.12]31% [14%, 47%]52%59%+0.27+0.252026-08-02 → 2026-08-30
tmax12Zbilinearall29 1 QC2.62 [1.86, 3.31]2.68-1.00 [-2.46, 0.44]3.41 [2.50, 4.10]31% [13%, 47%]52%59%+0.27+0.252026-08-02 → 2026-08-30
tmax12Znearest30d29 1 QC2.66 [1.99, 3.44]2.71-0.69 [-1.87, 0.54]3.37 [2.65, 4.01]31% [17%, 43%]48%59%+0.26+0.242026-08-02 → 2026-08-30
tmax12Znearest90d29 1 QC2.66 [1.96, 3.60]2.71-0.69 [-1.86, 0.66]3.37 [2.61, 4.15]31% [11%, 44%]48%59%+0.26+0.242026-08-02 → 2026-08-30
tmax12Znearest365d29 1 QC2.66 [1.90, 3.56]2.71-0.69 [-2.09, 0.64]3.37 [2.52, 4.16]31% [13%, 45%]48%59%+0.26+0.242026-08-02 → 2026-08-30
tmax12Znearestall29 1 QC2.66 [1.96, 3.59]2.71-0.69 [-2.04, 0.70]3.37 [2.59, 4.16]31% [12%, 44%]48%59%+0.26+0.242026-08-02 → 2026-08-30
tmin00Zbilinear30d29 1 QC2.44 [1.93, 3.06]2.43-0.70 [-1.93, 0.82]3.20 [2.39, 3.98]24% [14%, 34%]59%66%-0.02-0.022026-08-02 → 2026-08-30
tmin00Zbilinear90d29 1 QC2.44 [1.92, 3.07]2.43-0.70 [-2.00, 0.96]3.20 [2.34, 4.01]24% [14%, 33%]59%66%-0.02-0.022026-08-02 → 2026-08-30
tmin00Zbilinear365d29 1 QC2.44 [1.93, 3.15]2.43-0.70 [-2.15, 1.07]3.20 [2.31, 4.05]24% [14%, 35%]59%66%-0.02-0.022026-08-02 → 2026-08-30
tmin00Zbilinearall29 1 QC2.44 [1.86, 3.13]2.43-0.70 [-2.16, 1.17]3.20 [2.22, 3.95]24% [13%, 35%]59%66%-0.02-0.022026-08-02 → 2026-08-30
tmin00Znearest30d29 1 QC2.41 [1.83, 3.11]2.34-1.04 [-2.23, 0.45]3.18 [2.38, 3.98]31% [17%, 43%]59%69%-0.01+0.022026-08-02 → 2026-08-30
tmin00Znearest90d29 1 QC2.41 [1.78, 3.17]2.34-1.04 [-2.32, 0.56]3.18 [2.27, 3.98]31% [16%, 43%]59%69%-0.01+0.022026-08-02 → 2026-08-30
tmin00Znearest365d29 1 QC2.41 [1.70, 3.25]2.34-1.04 [-2.49, 0.67]3.18 [2.16, 4.05]31% [16%, 44%]59%69%-0.01+0.022026-08-02 → 2026-08-30
tmin00Znearestall29 1 QC2.41 [1.71, 3.24]2.34-1.04 [-2.49, 0.76]3.18 [2.18, 3.99]31% [14%, 43%]59%69%-0.01+0.022026-08-02 → 2026-08-30
tmin12Zbilinear30d29 1 QC2.42 [1.83, 3.08]2.42-0.47 [-1.70, 1.06]2.99 [2.36, 3.57]24% [13%, 38%]41%69%-0.02-0.022026-08-02 → 2026-08-30
tmin12Zbilinear90d29 1 QC2.42 [1.81, 3.10]2.42-0.47 [-1.81, 1.11]2.99 [2.28, 3.56]24% [10%, 39%]41%69%-0.02-0.022026-08-02 → 2026-08-30
tmin12Zbilinear365d29 1 QC2.42 [1.78, 3.16]2.42-0.47 [-1.87, 1.17]2.99 [2.29, 3.60]24% [10%, 41%]41%69%-0.02-0.022026-08-02 → 2026-08-30
tmin12Zbilinearall29 1 QC2.42 [1.70, 3.19]2.42-0.47 [-1.88, 1.26]2.99 [2.13, 3.60]24% [9%, 40%]41%69%-0.02-0.022026-08-02 → 2026-08-30
tmin12Znearest30d29 1 QC2.53 [1.97, 3.21]2.47-0.83 [-2.11, 0.80]3.11 [2.45, 3.73]28% [17%, 40%]48%66%-0.06-0.042026-08-02 → 2026-08-30
tmin12Znearest90d29 1 QC2.53 [1.92, 3.26]2.47-0.83 [-2.24, 0.91]3.11 [2.38, 3.76]28% [12%, 41%]48%66%-0.06-0.042026-08-02 → 2026-08-30
tmin12Znearest365d29 1 QC2.53 [1.88, 3.32]2.47-0.83 [-2.32, 0.97]3.11 [2.36, 3.78]28% [12%, 43%]48%66%-0.06-0.042026-08-02 → 2026-08-30
tmin12Znearestall29 1 QC2.53 [1.86, 3.31]2.47-0.83 [-2.33, 1.07]3.11 [2.28, 3.82]28% [12%, 41%]48%66%-0.06-0.042026-08-02 → 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 KDCA, lead day 1, 00Z bilinear tmax+20+100-10-202026-08-02: -6.29 °F2026-08-03: -5.56 °F2026-08-04: -1.72 °F2026-08-05: -9.52 °F2026-08-06: +3.97 °F2026-08-07: +3.43 °F2026-08-08: +0.03 °F2026-08-09: -1.27 °F2026-08-10: +3.25 °F2026-08-11: -4.77 °F2026-08-12: +0.27 °F2026-08-13: -0.46 °F2026-08-14: -8.77 °F2026-08-15: -0.65 °F2026-08-16: -7.6 °F2026-08-17: -6.75 °F2026-08-18: -0.12 °F2026-08-19: -0.97 °F2026-08-20: -4.44 °F2026-08-21: -12.97 °F2026-08-22: -8.07 °F2026-08-23: -3.08 °F2026-08-24: -1.31 °F2026-08-25: -3.54 °F2026-08-26: +1.32 °F2026-08-27: +1.86 °F2026-08-28: -2.22 °F2026-08-29: -3.42 °F2026-08-30: +0.8 °F2026-08-022026-08-30°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 (29 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+0.80
2026-08-29-3.42
2026-08-28-2.22
2026-08-27+1.86
2026-08-26+1.32
2026-08-25-3.54
2026-08-24-1.31
2026-08-23-3.08
2026-08-22-8.07
2026-08-21-12.97
2026-08-20-4.44
2026-08-19-0.97
2026-08-18-0.12
2026-08-17-6.75
2026-08-16-7.60
2026-08-15-0.65
2026-08-14-8.77
2026-08-13-0.46
2026-08-12+0.27
2026-08-11-4.77
2026-08-10+3.25
2026-08-09-1.27
2026-08-08+0.03
2026-08-07+3.43
2026-08-06+3.97
2026-08-05-9.52
2026-08-04-1.72
2026-08-03-5.56
2026-08-02-6.29

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KDCA, lead day 1-20 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: 0 days-10 to -8 °F: 3 days-8 to -6 °F: 3 days-6 to -4 °F: 3 days-4 to -2 °F: 4 days-2 to 0 °F: 7 days0 to 2 °F: 5 days2 to 4 °F: 3 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| 3.25 · P90 |e| 8.21 °F-200+20 °Fn = 29 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
-12.00-10.000
-10.00-8.003
-8.00-6.003
-6.00-4.003
-4.00-2.004
-2.00+0.007
+0.00+2.005
+2.00+4.003
+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
2026-08293.74 -2.71

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29
NCEP GFS2026-08-02 → 2026-08-30 29

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 29 +1.35 [0.16, 2.35] yes
Aurora (GFS init) 1 -7.28 [-7.28, -7.28] yes
Aurora (IFS init) 2 -3.97 [-5.86, -2.08] yes
FourCastNet v2 (GFS init) 1 -2.83 [-2.83, -2.83] yes
FourCastNet v2 (IFS init) 2 -0.33 [-2.20, 1.53] no
GraphCast (GFS init) 1 -4.33 [-4.33, -4.33] yes
GraphCast (IFS init) 27 -1.11 [-2.39, -0.22] yes
ECMWF IFS HRES 23 +0.05 [-1.28, 1.03] no
Pangu-Weather (GFS init) 1 -1.72 [-1.72, -1.72] yes
Pangu-Weather (IFS init) 2 +0.15 [-2.18, 2.48] no
Persistence (baseline) 29 +0.15 [-1.15, 1.64] no

Cite this page

ShortCastCheck, KDCA gfs lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDCA/model/gfs/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), model gfs, lead day 1. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KDCA/model/gfs/lead/1/

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