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 3

KDCA · gfs · lead 3

Target day = initialization date + 3 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
tmax00Zbilinear30d27 1 QC3.58 [2.54, 4.95]3.55-1.08 [-3.27, 0.91]4.87 [3.19, 6.37]30% [17%, 41%]33%59%+0.12+0.132026-08-04 → 2026-08-30
tmax00Zbilinear90d27 1 QC3.58 [2.53, 5.16]3.55-1.08 [-3.35, 0.94]4.87 [3.21, 6.53]30% [14%, 43%]33%59%+0.12+0.132026-08-04 → 2026-08-30
tmax00Zbilinear365d27 1 QC3.58 [2.41, 5.14]3.55-1.08 [-3.59, 1.07]4.87 [3.06, 6.58]30% [12%, 44%]33%59%+0.12+0.132026-08-04 → 2026-08-30
tmax00Zbilinearall27 1 QC3.58 [2.32, 5.40]3.55-1.08 [-3.74, 0.93]4.87 [2.85, 6.94]30% [14%, 44%]33%59%+0.12+0.132026-08-04 → 2026-08-30
tmax00Znearest30d27 1 QC3.68 [2.51, 5.26]3.59-1.00 [-3.28, 0.84]5.11 [3.13, 6.86]22% [10%, 32%]37%56%+0.10+0.122026-08-04 → 2026-08-30
tmax00Znearest90d27 1 QC3.68 [2.52, 5.52]3.59-1.00 [-3.42, 0.95]5.11 [3.15, 7.03]22% [9%, 31%]37%56%+0.10+0.122026-08-04 → 2026-08-30
tmax00Znearest365d27 1 QC3.68 [2.45, 5.42]3.59-1.00 [-3.55, 1.03]5.11 [3.04, 7.07]22% [8%, 32%]37%56%+0.10+0.122026-08-04 → 2026-08-30
tmax00Znearestall27 1 QC3.68 [2.20, 5.76]3.59-1.00 [-3.88, 1.00]5.11 [2.74, 7.50]22% [8%, 33%]37%56%+0.10+0.122026-08-04 → 2026-08-30
tmax12Zbilinear30d27 1 QC2.87 [2.10, 3.94]2.92-0.29 [-1.45, 0.86]4.06 [2.71, 5.51]33% [19%, 46%]48%67%+0.30+0.282026-08-04 → 2026-08-30
tmax12Zbilinear90d27 1 QC2.87 [2.06, 3.84]2.92-0.29 [-1.53, 0.90]4.06 [2.62, 5.41]33% [19%, 47%]48%67%+0.30+0.282026-08-04 → 2026-08-30
tmax12Zbilinear365d27 1 QC2.87 [2.03, 3.97]2.92-0.29 [-1.59, 0.96]4.06 [2.55, 5.52]33% [15%, 50%]48%67%+0.30+0.282026-08-04 → 2026-08-30
tmax12Zbilinearall27 1 QC2.87 [1.99, 3.98]2.92-0.29 [-1.60, 0.85]4.06 [2.56, 5.55]33% [17%, 50%]48%67%+0.30+0.282026-08-04 → 2026-08-30
tmax12Znearest30d27 1 QC2.99 [2.17, 4.21]2.99-0.02 [-1.22, 1.19]4.17 [2.72, 5.81]22% [4%, 40%]44%59%+0.27+0.272026-08-04 → 2026-08-30
tmax12Znearest90d27 1 QC2.99 [2.13, 4.13]2.99-0.02 [-1.26, 1.32]4.17 [2.62, 5.71]22% [0%, 41%]44%59%+0.27+0.272026-08-04 → 2026-08-30
tmax12Znearest365d27 1 QC2.99 [2.08, 4.21]2.99-0.02 [-1.36, 1.28]4.17 [2.55, 5.88]22% [0%, 43%]44%59%+0.27+0.272026-08-04 → 2026-08-30
tmax12Znearestall27 1 QC2.99 [2.03, 4.27]2.99-0.02 [-1.25, 1.21]4.17 [2.52, 5.84]22% [0%, 43%]44%59%+0.27+0.272026-08-04 → 2026-08-30
tmin00Zbilinear30d27 1 QC2.40 [2.04, 2.75]2.32-0.88 [-2.14, 0.61]2.85 [2.40, 3.25]15% [7%, 22%]44%74%+0.23+0.262026-08-04 → 2026-08-30
tmin00Zbilinear90d27 1 QC2.40 [2.03, 2.74]2.32-0.88 [-2.17, 0.76]2.85 [2.35, 3.24]15% [7%, 24%]44%74%+0.23+0.262026-08-04 → 2026-08-30
tmin00Zbilinear365d27 1 QC2.40 [2.05, 2.75]2.32-0.88 [-2.24, 0.78]2.85 [2.36, 3.26]15% [6%, 23%]44%74%+0.23+0.262026-08-04 → 2026-08-30
tmin00Zbilinearall27 1 QC2.40 [1.93, 2.76]2.32-0.88 [-2.18, 0.94]2.85 [2.20, 3.25]15% [6%, 23%]44%74%+0.23+0.262026-08-04 → 2026-08-30
tmin00Znearest30d27 1 QC2.55 [2.05, 3.06]2.40-1.37 [-2.72, 0.22]3.08 [2.41, 3.63]19% [9%, 27%]37%67%+0.18+0.232026-08-04 → 2026-08-30
tmin00Znearest90d27 1 QC2.55 [1.99, 3.03]2.40-1.37 [-2.75, 0.36]3.08 [2.31, 3.61]19% [8%, 27%]37%67%+0.18+0.232026-08-04 → 2026-08-30
tmin00Znearest365d27 1 QC2.55 [1.90, 3.12]2.40-1.37 [-2.86, 0.43]3.08 [2.15, 3.68]19% [8%, 27%]37%67%+0.18+0.232026-08-04 → 2026-08-30
tmin00Znearestall27 1 QC2.55 [1.89, 3.08]2.40-1.37 [-2.82, 0.61]3.08 [2.11, 3.63]19% [8%, 28%]37%67%+0.18+0.232026-08-04 → 2026-08-30
tmin12Zbilinear30d27 1 QC2.25 [1.92, 2.64]2.23-0.66 [-1.95, 0.88]2.84 [2.41, 3.29]26% [14%, 39%]56%67%+0.28+0.292026-08-04 → 2026-08-30
tmin12Zbilinear90d27 1 QC2.25 [1.90, 2.62]2.23-0.66 [-2.10, 0.93]2.84 [2.36, 3.26]26% [14%, 40%]56%67%+0.28+0.292026-08-04 → 2026-08-30
tmin12Zbilinear365d27 1 QC2.25 [1.91, 2.70]2.23-0.66 [-2.14, 1.05]2.84 [2.36, 3.30]26% [12%, 43%]56%67%+0.28+0.292026-08-04 → 2026-08-30
tmin12Zbilinearall27 1 QC2.25 [1.89, 2.65]2.23-0.66 [-2.14, 1.20]2.84 [2.32, 3.28]26% [13%, 43%]56%67%+0.28+0.292026-08-04 → 2026-08-30
tmin12Znearest30d27 1 QC2.36 [2.03, 2.80]2.23-1.11 [-2.39, 0.42]2.99 [2.47, 3.53]26% [17%, 33%]52%63%+0.24+0.292026-08-04 → 2026-08-30
tmin12Znearest90d27 1 QC2.36 [2.03, 2.82]2.23-1.11 [-2.50, 0.45]2.99 [2.43, 3.58]26% [17%, 33%]52%63%+0.24+0.292026-08-04 → 2026-08-30
tmin12Znearest365d27 1 QC2.36 [2.00, 2.87]2.23-1.11 [-2.60, 0.64]2.99 [2.37, 3.67]26% [15%, 35%]52%63%+0.24+0.292026-08-04 → 2026-08-30
tmin12Znearestall27 1 QC2.36 [1.99, 2.88]2.23-1.11 [-2.61, 0.71]2.99 [2.36, 3.66]26% [15%, 33%]52%63%+0.24+0.292026-08-04 → 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 3, 00Z bilinear tmax+20+100-10-202026-08-04: -12.04 °F2026-08-05: -7.07 °F2026-08-06: +4.45 °F2026-08-07: +2.1 °F2026-08-08: -0.43 °F2026-08-09: -2.13 °F2026-08-10: +2.6 °F2026-08-11: +5.39 °F2026-08-12: -0.19 °F2026-08-13: +0.43 °F2026-08-14: +2.87 °F2026-08-15: +0.69 °F2026-08-16: +12.54 °F2026-08-17: -8.81 °F2026-08-18: -2.23 °F2026-08-19: +1.34 °F2026-08-20: -2.59 °F2026-08-21: -0.49 °F2026-08-22: -3.42 °F2026-08-23: -5.02 °F2026-08-24: -2.47 °F2026-08-25: -0.97 °F2026-08-26: +0.43 °F2026-08-27: -4.1 °F2026-08-28: -6.4 °F2026-08-29: -4.61 °F2026-08-30: +0.87 °F2026-08-042026-08-30°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 (27 days, newest first) · download CSV
Climatological dayError °F
2026-08-30+0.87
2026-08-29-4.61
2026-08-28-6.40
2026-08-27-4.10
2026-08-26+0.43
2026-08-25-0.97
2026-08-24-2.47
2026-08-23-5.02
2026-08-22-3.42
2026-08-21-0.49
2026-08-20-2.59
2026-08-19+1.34
2026-08-18-2.23
2026-08-17-8.81
2026-08-16+12.54
2026-08-15+0.69
2026-08-14+2.87
2026-08-13+0.43
2026-08-12-0.19
2026-08-11+5.39
2026-08-10+2.60
2026-08-09-2.13
2026-08-08-0.43
2026-08-07+2.10
2026-08-06+4.45
2026-08-05-7.07
2026-08-04-12.04

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KDCA, lead day 3-20 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: 1 day-8 to -6 °F: 2 days-6 to -4 °F: 3 days-4 to -2 °F: 5 days-2 to 0 °F: 4 days0 to 2 °F: 5 days2 to 4 °F: 3 days4 to 6 °F: 2 days6 to 8 °F: 0 days8 to 10 °F: 0 days10 to 12 °F: 0 days12 to 14 °F: 1 day14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 2.59 · P90 |e| 7.77 °F-200+20 °Fn = 27 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
-10.00-8.001
-8.00-6.002
-6.00-4.003
-4.00-2.005
-2.00+0.004
+0.00+2.005
+2.00+4.003
+4.00+6.002
+6.00+8.000
+8.00+10.000
+10.00+12.000
+12.00+14.001
+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
2026-08273.58 -1.08

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27
NCEP GFS2026-08-04 → 2026-08-30 27

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 27 +0.56 [-0.73, 2.35] no
GraphCast (IFS init) 25 -1.21 [-2.75, 0.46] no
ECMWF IFS HRES 22 -0.25 [-1.94, 3.45] no
Persistence (baseline) 27 -0.49 [-1.80, 1.85] no

Cite this page

ShortCastCheck, KDCA gfs lead 3, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDCA/model/gfs/lead/3/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), model gfs, lead day 3. 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/3/

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