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 9

KDCA · gfs · lead 9

Target day = initialization date + 9 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
tmax00Zbilinear30d21 1 QC7.28 [5.97, 8.26]6.93-1.61 [-5.54, 2.71]8.65 [7.34, 9.64]5% [0%, 13%]19%29%-0.76-0.752026-08-10 → 2026-08-30
tmax00Zbilinear90d21 1 QC7.28 [5.72, 8.29]6.93-1.61 [-6.39, 2.96]8.65 [7.04, 9.64]5% [0%, 13%]19%29%-0.76-0.752026-08-10 → 2026-08-30
tmax00Zbilinear365d21 1 QC7.28 [5.72, 8.48]6.93-1.61 [-6.45, 3.20]8.65 [7.13, 10.05]5% [0%, 14%]19%29%-0.76-0.752026-08-10 → 2026-08-30
tmax00Zbilinearall21 1 QC7.28 [5.79, 8.39]6.93-1.61 [-6.45, 4.01]8.65 [7.00, 9.70]5% [0%, 14%]19%29%-0.76-0.752026-08-10 → 2026-08-30
tmax00Znearest30d21 1 QC7.56 [6.22, 8.65]7.35-1.53 [-5.72, 3.13]9.03 [7.52, 10.17]10% [0%, 22%]19%29%-0.82-0.852026-08-10 → 2026-08-30
tmax00Znearest90d21 1 QC7.56 [5.87, 8.60]7.35-1.53 [-6.46, 3.22]9.03 [7.20, 10.20]10% [0%, 23%]19%29%-0.82-0.852026-08-10 → 2026-08-30
tmax00Znearest365d21 1 QC7.56 [5.97, 8.89]7.35-1.53 [-6.47, 3.55]9.03 [7.20, 10.53]10% [0%, 24%]19%29%-0.82-0.852026-08-10 → 2026-08-30
tmax00Znearestall21 1 QC7.56 [6.09, 8.69]7.35-1.53 [-6.60, 4.58]9.03 [7.20, 10.25]10% [0%, 24%]19%29%-0.82-0.852026-08-10 → 2026-08-30
tmax12Zbilinear30d21 1 QC7.45 [5.26, 9.32]7.26-2.10 [-5.50, 0.67]8.74 [5.81, 10.72]5% [0%, 20%]14%14%-0.80-0.832026-08-10 → 2026-08-30
tmax12Zbilinear90d21 1 QC7.45 [5.02, 9.63]7.26-2.10 [-6.10, 0.99]8.74 [5.59, 10.93]5% [0%, 24%]14%14%-0.80-0.832026-08-10 → 2026-08-30
tmax12Zbilinear365d21 1 QC7.45 [4.91, 9.57]7.26-2.10 [-6.08, 1.34]8.74 [5.49, 10.91]5% [0%, 22%]14%14%-0.80-0.832026-08-10 → 2026-08-30
tmax12Zbilinearall21 1 QC7.45 [4.78, 9.58]7.26-2.10 [-6.07, 1.34]8.74 [5.41, 10.77]5% [0%, 30%]14%14%-0.80-0.832026-08-10 → 2026-08-30
tmax12Znearest30d21 1 QC7.37 [5.26, 9.20]7.18-2.11 [-5.23, 0.47]8.58 [5.79, 10.49]10% [0%, 25%]14%14%-0.78-0.812026-08-10 → 2026-08-30
tmax12Znearest90d21 1 QC7.37 [5.06, 9.50]7.18-2.11 [-5.80, 0.77]8.58 [5.53, 10.72]10% [0%, 29%]14%14%-0.78-0.812026-08-10 → 2026-08-30
tmax12Znearest365d21 1 QC7.37 [4.91, 9.46]7.18-2.11 [-5.79, 1.08]8.58 [5.44, 10.71]10% [0%, 31%]14%14%-0.78-0.812026-08-10 → 2026-08-30
tmax12Znearestall21 1 QC7.37 [4.85, 9.44]7.18-2.11 [-5.80, 1.13]8.58 [5.38, 10.59]10% [0%, 33%]14%14%-0.78-0.812026-08-10 → 2026-08-30
tmin00Zbilinear30d21 1 QC4.95 [3.47, 5.82]5.03-0.57 [-4.07, 3.26]6.24 [4.92, 6.84]14% [0%, 29%]29%43%-0.21-0.262026-08-10 → 2026-08-30
tmin00Zbilinear90d21 1 QC4.95 [2.97, 5.84]5.03-0.57 [-4.21, 3.36]6.24 [4.27, 6.81]14% [0%, 33%]29%43%-0.21-0.262026-08-10 → 2026-08-30
tmin00Zbilinear365d21 1 QC4.95 [2.97, 5.88]5.03-0.57 [-4.43, 3.73]6.24 [4.36, 6.83]14% [0%, 33%]29%43%-0.21-0.262026-08-10 → 2026-08-30
tmin00Zbilinearall21 1 QC4.95 [2.86, 5.89]5.03-0.57 [-4.51, 4.58]6.24 [3.79, 6.83]14% [0%, 33%]29%43%-0.21-0.262026-08-10 → 2026-08-30
tmin00Znearest30d21 1 QC4.77 [3.22, 5.62]4.83-1.17 [-4.46, 2.43]6.05 [4.73, 6.68]19% [0%, 40%]33%43%-0.16-0.212026-08-10 → 2026-08-30
tmin00Znearest90d21 1 QC4.77 [2.45, 5.59]4.83-1.17 [-4.60, 2.58]6.05 [4.12, 6.68]19% [0%, 43%]33%43%-0.16-0.212026-08-10 → 2026-08-30
tmin00Znearest365d21 1 QC4.77 [2.79, 5.64]4.83-1.17 [-4.76, 2.96]6.05 [4.11, 6.77]19% [0%, 43%]33%43%-0.16-0.212026-08-10 → 2026-08-30
tmin00Znearestall21 1 QC4.77 [2.49, 5.62]4.83-1.17 [-4.92, 3.87]6.05 [3.53, 6.72]19% [0%, 40%]33%43%-0.16-0.212026-08-10 → 2026-08-30
tmin12Zbilinear30d21 1 QC4.71 [3.75, 5.37]4.56-0.76 [-3.78, 2.65]5.69 [4.55, 6.38]10% [0%, 21%]24%43%-0.15-0.152026-08-10 → 2026-08-30
tmin12Zbilinear90d21 1 QC4.71 [3.70, 5.38]4.56-0.76 [-3.92, 3.32]5.69 [4.54, 6.45]10% [0%, 22%]24%43%-0.15-0.152026-08-10 → 2026-08-30
tmin12Zbilinear365d21 1 QC4.71 [3.60, 5.55]4.56-0.76 [-4.18, 3.38]5.69 [4.50, 6.54]10% [0%, 22%]24%43%-0.15-0.152026-08-10 → 2026-08-30
tmin12Zbilinearall21 1 QC4.71 [3.49, 5.42]4.56-0.76 [-4.28, 3.52]5.69 [4.35, 6.43]10% [0%, 21%]24%43%-0.15-0.152026-08-10 → 2026-08-30
tmin12Znearest30d21 1 QC4.80 [3.83, 5.46]4.65-1.08 [-4.21, 2.44]5.79 [4.49, 6.61]14% [0%, 26%]24%43%-0.17-0.172026-08-10 → 2026-08-30
tmin12Znearest90d21 1 QC4.80 [3.86, 5.49]4.65-1.08 [-4.34, 3.05]5.79 [4.51, 6.63]14% [0%, 29%]24%43%-0.17-0.172026-08-10 → 2026-08-30
tmin12Znearest365d21 1 QC4.80 [3.79, 5.66]4.65-1.08 [-4.63, 3.30]5.79 [4.46, 6.78]14% [0%, 29%]24%43%-0.17-0.172026-08-10 → 2026-08-30
tmin12Znearestall21 1 QC4.80 [3.75, 5.66]4.65-1.08 [-4.73, 3.40]5.79 [4.37, 6.71]14% [0%, 29%]24%43%-0.17-0.172026-08-10 → 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 9, 00Z bilinear tmax+20+100-10-202026-08-10: +1.33 °F2026-08-11: +10.12 °F2026-08-12: +8.64 °F2026-08-13: -11.48 °F2026-08-14: -3.88 °F2026-08-15: -3.56 °F2026-08-16: -6.52 °F2026-08-17: -14.54 °F2026-08-18: -2.54 °F2026-08-19: -9.32 °F2026-08-20: +0.18 °F2026-08-21: +11.61 °F2026-08-22: +16.39 °F2026-08-23: -1.38 °F2026-08-24: +2.17 °F2026-08-25: +9.06 °F2026-08-26: -9.99 °F2026-08-27: -10.75 °F2026-08-28: -11.74 °F2026-08-29: -1.4 °F2026-08-30: -6.2 °F2026-08-102026-08-30°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 (21 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-6.20
2026-08-29-1.40
2026-08-28-11.74
2026-08-27-10.75
2026-08-26-9.99
2026-08-25+9.06
2026-08-24+2.17
2026-08-23-1.38
2026-08-22+16.39
2026-08-21+11.61
2026-08-20+0.18
2026-08-19-9.32
2026-08-18-2.54
2026-08-17-14.54
2026-08-16-6.52
2026-08-15-3.56
2026-08-14-3.88
2026-08-13-11.48
2026-08-12+8.64
2026-08-11+10.12
2026-08-10+1.33

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KDCA, lead day 9-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 1 day-14 to -12 °F: 0 days-12 to -10 °F: 3 days-10 to -8 °F: 2 days-8 to -6 °F: 2 days-6 to -4 °F: 0 days-4 to -2 °F: 3 days-2 to 0 °F: 2 days0 to 2 °F: 2 days2 to 4 °F: 1 day4 to 6 °F: 0 days6 to 8 °F: 0 days8 to 10 °F: 2 days10 to 12 °F: 2 days12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 1 day18 to 20 °F: 0 daysdashed: P50 |e| 8.64 · P90 |e| 11.74 °F-200+20 °Fn = 21 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
-16.00-14.001
-14.00-12.000
-12.00-10.003
-10.00-8.002
-8.00-6.002
-6.00-4.000
-4.00-2.003
-2.00+0.002
+0.00+2.002
+2.00+4.001
+4.00+6.000
+6.00+8.000
+8.00+10.002
+10.00+12.002
+12.00+14.000
+14.00+16.000
+16.00+18.001
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08217.28 -1.61

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21
NCEP GFS2026-08-10 → 2026-08-30 21

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 21 +2.72 [0.76, 4.47] yes
GraphCast (IFS init) 21 +0.81 [-2.05, 2.49] no
ECMWF IFS HRES 16 +2.84 [-2.26, 4.60] no
Persistence (baseline) 21 +3.13 [1.23, 4.17] yes

Cite this page

ShortCastCheck, KDCA gfs lead 9, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KDCA/model/gfs/lead/9/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KDCA (Washington Reagan), model gfs, lead day 9. 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/9/

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