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 7

KDCA · gfs · lead 7

Target day = initialization date + 7 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
tmax00Zbilinear30d23 1 QC4.47 [3.19, 5.54]4.13-2.82 [-4.78, 0.16]5.96 [4.04, 7.75]17% [5%, 30%]30%43%+0.01+0.092026-08-08 → 2026-08-30
tmax00Zbilinear90d23 1 QC4.47 [3.02, 5.43]4.13-2.82 [-4.80, 1.34]5.96 [3.75, 7.75]17% [4%, 31%]30%43%+0.01+0.092026-08-08 → 2026-08-30
tmax00Zbilinear365d23 1 QC4.47 [2.87, 5.49]4.13-2.82 [-4.81, 1.27]5.96 [3.76, 7.93]17% [3%, 31%]30%43%+0.01+0.092026-08-08 → 2026-08-30
tmax00Zbilinearall23 1 QC4.47 [2.72, 5.51]4.13-2.82 [-4.81, 1.32]5.96 [3.47, 7.90]17% [0%, 31%]30%43%+0.01+0.092026-08-08 → 2026-08-30
tmax00Znearest30d23 1 QC4.36 [3.10, 5.54]4.02-2.42 [-4.32, 0.52]5.74 [3.87, 7.58]13% [0%, 35%]35%43%+0.04+0.122026-08-08 → 2026-08-30
tmax00Znearest90d23 1 QC4.36 [3.03, 5.45]4.02-2.42 [-4.31, 1.53]5.74 [3.75, 7.64]13% [0%, 41%]35%43%+0.04+0.122026-08-08 → 2026-08-30
tmax00Znearest365d23 1 QC4.36 [2.83, 5.56]4.02-2.42 [-4.35, 1.50]5.74 [3.49, 7.85]13% [0%, 43%]35%43%+0.04+0.122026-08-08 → 2026-08-30
tmax00Znearestall23 1 QC4.36 [2.71, 5.56]4.02-2.42 [-4.33, 1.58]5.74 [3.47, 7.81]13% [0%, 44%]35%43%+0.04+0.122026-08-08 → 2026-08-30
tmax12Zbilinear30d23 1 QC4.97 [2.79, 6.85]5.09-0.72 [-2.68, 1.68]6.83 [3.71, 8.64]17% [0%, 35%]26%48%-0.10-0.122026-08-08 → 2026-08-30
tmax12Zbilinear90d23 1 QC4.97 [2.71, 6.89]5.09-0.72 [-2.72, 2.63]6.83 [3.23, 8.68]17% [0%, 36%]26%48%-0.10-0.122026-08-08 → 2026-08-30
tmax12Zbilinear365d23 1 QC4.97 [2.37, 6.80]5.09-0.72 [-2.68, 2.07]6.83 [2.68, 8.61]17% [0%, 36%]26%48%-0.10-0.122026-08-08 → 2026-08-30
tmax12Zbilinearall23 1 QC4.97 [2.09, 7.13]5.09-0.72 [-2.81, 2.38]6.83 [2.53, 8.78]17% [0%, 43%]26%48%-0.10-0.122026-08-08 → 2026-08-30
tmax12Znearest30d23 1 QC5.03 [2.92, 6.89]5.09-0.28 [-2.30, 2.10]6.86 [3.84, 8.58]9% [0%, 21%]26%39%-0.11-0.122026-08-08 → 2026-08-30
tmax12Znearest90d23 1 QC5.03 [2.84, 6.89]5.09-0.28 [-2.28, 3.25]6.86 [3.58, 8.67]9% [0%, 23%]26%39%-0.11-0.122026-08-08 → 2026-08-30
tmax12Znearest365d23 1 QC5.03 [2.56, 6.80]5.09-0.28 [-2.25, 2.53]6.86 [3.05, 8.60]9% [0%, 25%]26%39%-0.11-0.122026-08-08 → 2026-08-30
tmax12Znearestall23 1 QC5.03 [2.29, 7.13]5.09-0.28 [-2.49, 3.00]6.86 [2.62, 8.79]9% [0%, 26%]26%39%-0.11-0.122026-08-08 → 2026-08-30
tmin00Zbilinear30d23 1 QC3.76 [2.11, 5.10]3.92-1.00 [-3.75, 1.70]5.03 [2.78, 6.38]26% [17%, 36%]48%48%+0.21+0.172026-08-08 → 2026-08-30
tmin00Zbilinear90d23 1 QC3.76 [1.82, 5.10]3.92-1.00 [-3.91, 1.67]5.03 [2.47, 6.41]26% [17%, 38%]48%48%+0.21+0.172026-08-08 → 2026-08-30
tmin00Zbilinear365d23 1 QC3.76 [1.80, 5.20]3.92-1.00 [-3.94, 1.91]5.03 [2.46, 6.52]26% [18%, 38%]48%48%+0.21+0.172026-08-08 → 2026-08-30
tmin00Zbilinearall23 1 QC3.76 [1.62, 5.18]3.92-1.00 [-4.01, 2.39]5.03 [1.81, 6.47]26% [15%, 38%]48%48%+0.21+0.172026-08-08 → 2026-08-30
tmin00Znearest30d23 1 QC3.86 [2.30, 5.20]3.94-1.35 [-4.09, 1.43]5.05 [3.00, 6.43]26% [15%, 44%]39%52%+0.18+0.162026-08-08 → 2026-08-30
tmin00Znearest90d23 1 QC3.86 [1.97, 5.15]3.94-1.35 [-4.27, 1.33]5.05 [2.60, 6.44]26% [14%, 50%]39%52%+0.18+0.162026-08-08 → 2026-08-30
tmin00Znearest365d23 1 QC3.86 [1.90, 5.30]3.94-1.35 [-4.26, 1.58]5.05 [2.61, 6.51]26% [14%, 50%]39%52%+0.18+0.162026-08-08 → 2026-08-30
tmin00Znearestall23 1 QC3.86 [1.86, 5.19]3.94-1.35 [-4.33, 2.08]5.05 [2.28, 6.56]26% [14%, 50%]39%52%+0.18+0.162026-08-08 → 2026-08-30
tmin12Zbilinear30d23 1 QC4.01 [3.00, 5.10]3.87-1.24 [-3.52, 0.93]4.92 [3.58, 6.27]9% [0%, 16%]30%52%+0.15+0.182026-08-08 → 2026-08-30
tmin12Zbilinear90d23 1 QC4.01 [2.98, 5.13]3.87-1.24 [-3.61, 0.95]4.92 [3.53, 6.26]9% [0%, 14%]30%52%+0.15+0.182026-08-08 → 2026-08-30
tmin12Zbilinear365d23 1 QC4.01 [3.02, 5.23]3.87-1.24 [-3.67, 1.12]4.92 [3.57, 6.39]9% [0%, 14%]30%52%+0.15+0.182026-08-08 → 2026-08-30
tmin12Zbilinearall23 1 QC4.01 [2.94, 5.27]3.87-1.24 [-3.90, 1.38]4.92 [3.48, 6.41]9% [0%, 14%]30%52%+0.15+0.182026-08-08 → 2026-08-30
tmin12Znearest30d23 1 QC3.81 [2.65, 5.12]3.57-1.64 [-3.88, 0.50]4.84 [3.26, 6.30]17% [6%, 28%]35%52%+0.20+0.242026-08-08 → 2026-08-30
tmin12Znearest90d23 1 QC3.81 [2.61, 5.13]3.57-1.64 [-4.00, 0.54]4.84 [3.12, 6.31]17% [5%, 29%]35%52%+0.20+0.242026-08-08 → 2026-08-30
tmin12Znearest365d23 1 QC3.81 [2.63, 5.18]3.57-1.64 [-4.07, 0.71]4.84 [3.15, 6.40]17% [0%, 29%]35%52%+0.20+0.242026-08-08 → 2026-08-30
tmin12Znearestall23 1 QC3.81 [2.60, 5.26]3.57-1.64 [-4.23, 1.00]4.84 [2.97, 6.51]17% [0%, 29%]35%52%+0.20+0.242026-08-08 → 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 7, 00Z bilinear tmax+20+100-10-202026-08-08: +4.59 °F2026-08-09: +0.34 °F2026-08-10: +3.27 °F2026-08-11: +6.88 °F2026-08-12: -6.62 °F2026-08-13: -3.42 °F2026-08-14: -2.27 °F2026-08-15: -5.98 °F2026-08-16: -2.01 °F2026-08-17: -9.6 °F2026-08-18: -5.1 °F2026-08-19: -1.1 °F2026-08-20: -7.6 °F2026-08-21: +0.7 °F2026-08-22: -3.61 °F2026-08-23: -1.7 °F2026-08-24: -5.09 °F2026-08-25: +0.59 °F2026-08-26: -14.23 °F2026-08-27: -14.48 °F2026-08-28: +0.28 °F2026-08-29: +2.39 °F2026-08-30: -1.07 °F2026-08-082026-08-30°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 (23 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-1.07
2026-08-29+2.39
2026-08-28+0.28
2026-08-27-14.48
2026-08-26-14.23
2026-08-25+0.59
2026-08-24-5.09
2026-08-23-1.70
2026-08-22-3.61
2026-08-21+0.70
2026-08-20-7.60
2026-08-19-1.10
2026-08-18-5.10
2026-08-17-9.60
2026-08-16-2.01
2026-08-15-5.98
2026-08-14-2.27
2026-08-13-3.42
2026-08-12-6.62
2026-08-11+6.88
2026-08-10+3.27
2026-08-09+0.34
2026-08-08+4.59

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KDCA, lead day 7-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 2 days-14 to -12 °F: 0 days-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: 4 days-2 to 0 °F: 3 days0 to 2 °F: 4 days2 to 4 °F: 2 days4 to 6 °F: 1 day6 to 8 °F: 1 day8 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| 3.42 · P90 |e| 9.2 °F-200+20 °Fn = 23 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
-16.00-14.002
-14.00-12.000
-12.00-10.000
-10.00-8.001
-8.00-6.002
-6.00-4.003
-4.00-2.004
-2.00+0.003
+0.00+2.004
+2.00+4.002
+4.00+6.001
+6.00+8.001
+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
2026-08234.47 -2.82

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23
NCEP GFS2026-08-08 → 2026-08-30 23

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 23 +1.21 [-0.87, 2.35] no
GraphCast (IFS init) 23 -0.35 [-2.48, 0.96] no
ECMWF IFS HRES 18 +0.72 [-1.02, 2.68] no
Persistence (baseline) 23 -0.05 [-1.80, 0.99] no

Cite this page

ShortCastCheck, KDCA gfs lead 7, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDCA/model/gfs/lead/7/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), model gfs, lead day 7. 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/7/

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