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CastCheck methodology v0.2 · data through 2026-08-30

All stations (mean of daily station errors) · ECMWF AIFS Single · lead day 4

ALL · aifs_single · lead 4

Target day = initialization date + 4 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, aifs-single-gpid5, 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
tmax00Zbilinear30d26 2 QC3.68 [3.53, 3.85]0.58-3.16 [-3.37, -2.96]4.33 [4.20, 4.48]13% [11%, 15%]26%40%+0.05+0.602026-08-05 → 2026-08-30
tmax00Zbilinear90d26 2 QC3.68 [3.52, 3.87]0.58-3.16 [-3.40, -2.94]4.33 [4.19, 4.48]13% [11%, 15%]26%40%+0.05+0.602026-08-05 → 2026-08-30
tmax00Zbilinear365d26 2 QC3.68 [3.50, 3.88]0.58-3.16 [-3.42, -2.92]4.33 [4.19, 4.51]13% [11%, 15%]26%40%+0.05+0.602026-08-05 → 2026-08-30
tmax00Zbilinearall26 2 QC3.68 [3.50, 3.89]0.58-3.16 [-3.42, -2.94]4.33 [4.18, 4.52]13% [11%, 15%]26%40%+0.05+0.602026-08-05 → 2026-08-30
tmax00Znearest30d26 2 QC3.71 [3.54, 3.89]0.57-3.10 [-3.31, -2.90]4.39 [4.21, 4.56]13% [12%, 15%]26%42%+0.04+0.602026-08-05 → 2026-08-30
tmax00Znearest90d26 2 QC3.71 [3.52, 3.91]0.57-3.10 [-3.35, -2.88]4.39 [4.20, 4.57]13% [11%, 14%]26%42%+0.04+0.602026-08-05 → 2026-08-30
tmax00Znearest365d26 2 QC3.71 [3.52, 3.92]0.57-3.10 [-3.37, -2.87]4.39 [4.19, 4.59]13% [12%, 15%]26%42%+0.04+0.602026-08-05 → 2026-08-30
tmax00Znearestall26 2 QC3.71 [3.52, 3.92]0.57-3.10 [-3.37, -2.88]4.39 [4.20, 4.59]13% [12%, 15%]26%42%+0.04+0.602026-08-05 → 2026-08-30
tmax12Zbilinear30d26 2 QC3.70 [3.57, 3.86]0.56-3.20 [-3.41, -2.98]4.29 [4.15, 4.45]11% [9%, 13%]24%41%+0.04+0.612026-08-05 → 2026-08-30
tmax12Zbilinear90d26 2 QC3.70 [3.54, 3.88]0.56-3.20 [-3.46, -2.94]4.29 [4.12, 4.45]11% [9%, 13%]24%41%+0.04+0.612026-08-05 → 2026-08-30
tmax12Zbilinear365d26 2 QC3.70 [3.54, 3.91]0.56-3.20 [-3.47, -2.91]4.29 [4.12, 4.47]11% [9%, 13%]24%41%+0.04+0.612026-08-05 → 2026-08-30
tmax12Zbilinearall26 2 QC3.70 [3.54, 3.94]0.56-3.20 [-3.48, -2.93]4.29 [4.12, 4.49]11% [9%, 13%]24%41%+0.04+0.612026-08-05 → 2026-08-30
tmax12Znearest30d26 2 QC3.74 [3.61, 3.90]0.55-3.13 [-3.35, -2.91]4.35 [4.20, 4.52]12% [11%, 13%]24%40%+0.03+0.622026-08-05 → 2026-08-30
tmax12Znearest90d26 2 QC3.74 [3.60, 3.91]0.55-3.13 [-3.40, -2.88]4.35 [4.19, 4.52]12% [10%, 14%]24%40%+0.03+0.622026-08-05 → 2026-08-30
tmax12Znearest365d26 2 QC3.74 [3.59, 3.92]0.55-3.13 [-3.41, -2.86]4.35 [4.19, 4.53]12% [11%, 14%]24%40%+0.03+0.622026-08-05 → 2026-08-30
tmax12Znearestall26 2 QC3.74 [3.60, 3.95]0.55-3.13 [-3.41, -2.87]4.35 [4.19, 4.57]12% [11%, 14%]24%40%+0.03+0.622026-08-05 → 2026-08-30
tmin00Zbilinear30d26 2 QC2.43 [2.14, 2.72]0.60+0.39 [0.10, 0.69]3.16 [2.79, 3.51]28% [24%, 34%]51%70%+0.21+0.232026-08-05 → 2026-08-30
tmin00Zbilinear90d26 2 QC2.43 [2.09, 2.76]0.60+0.39 [0.07, 0.73]3.16 [2.77, 3.56]28% [23%, 36%]51%70%+0.21+0.232026-08-05 → 2026-08-30
tmin00Zbilinear365d26 2 QC2.43 [2.08, 2.78]0.60+0.39 [0.06, 0.73]3.16 [2.74, 3.59]28% [23%, 36%]51%70%+0.21+0.232026-08-05 → 2026-08-30
tmin00Zbilinearall26 2 QC2.43 [2.08, 2.78]0.60+0.39 [0.03, 0.71]3.16 [2.75, 3.60]28% [23%, 36%]51%70%+0.21+0.232026-08-05 → 2026-08-30
tmin00Znearest30d26 2 QC2.51 [2.19, 2.81]0.61+0.36 [0.06, 0.67]3.27 [2.88, 3.60]26% [21%, 32%]50%68%+0.19+0.222026-08-05 → 2026-08-30
tmin00Znearest90d26 2 QC2.51 [2.14, 2.85]0.61+0.36 [0.04, 0.71]3.27 [2.85, 3.65]26% [20%, 34%]50%68%+0.19+0.222026-08-05 → 2026-08-30
tmin00Znearest365d26 2 QC2.51 [2.13, 2.87]0.61+0.36 [0.01, 0.72]3.27 [2.83, 3.68]26% [19%, 35%]50%68%+0.19+0.222026-08-05 → 2026-08-30
tmin00Znearestall26 2 QC2.51 [2.14, 2.87]0.61+0.36 [-0.02, 0.69]3.27 [2.84, 3.69]26% [20%, 34%]50%68%+0.19+0.222026-08-05 → 2026-08-30
tmin12Zbilinear30d26 2 QC2.36 [2.15, 2.59]0.57+0.25 [-0.01, 0.50]3.06 [2.76, 3.37]28% [24%, 31%]53%71%+0.24+0.272026-08-05 → 2026-08-30
tmin12Zbilinear90d26 2 QC2.36 [2.14, 2.61]0.57+0.25 [-0.03, 0.54]3.06 [2.75, 3.40]28% [24%, 32%]53%71%+0.24+0.272026-08-05 → 2026-08-30
tmin12Zbilinear365d26 2 QC2.36 [2.13, 2.63]0.57+0.25 [-0.02, 0.56]3.06 [2.71, 3.43]28% [23%, 32%]53%71%+0.24+0.272026-08-05 → 2026-08-30
tmin12Zbilinearall26 2 QC2.36 [2.13, 2.63]0.57+0.25 [-0.04, 0.54]3.06 [2.74, 3.44]28% [24%, 32%]53%71%+0.24+0.272026-08-05 → 2026-08-30
tmin12Znearest30d26 2 QC2.43 [2.20, 2.68]0.58+0.23 [-0.04, 0.48]3.16 [2.85, 3.46]28% [23%, 33%]52%70%+0.21+0.262026-08-05 → 2026-08-30
tmin12Znearest90d26 2 QC2.43 [2.17, 2.70]0.58+0.23 [-0.07, 0.52]3.16 [2.83, 3.49]28% [23%, 34%]52%70%+0.21+0.262026-08-05 → 2026-08-30
tmin12Znearest365d26 2 QC2.43 [2.17, 2.72]0.58+0.23 [-0.07, 0.53]3.16 [2.80, 3.51]28% [22%, 34%]52%70%+0.21+0.262026-08-05 → 2026-08-30
tmin12Znearestall26 2 QC2.43 [2.17, 2.73]0.58+0.23 [-0.08, 0.51]3.16 [2.82, 3.53]28% [22%, 34%]52%70%+0.21+0.262026-08-05 → 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 ECMWF AIFS Single at ALL, lead day 4, 00Z bilinear tmax+5+2.50-2.5-52026-08-05: -3.82 °F2026-08-06: -3.54 °F2026-08-07: -3.8 °F2026-08-08: -2.83 °F2026-08-09: -2.47 °F2026-08-10: -2.22 °F2026-08-11: -3.52 °F2026-08-12: -4.33 °F2026-08-13: -2.76 °F2026-08-14: -3.64 °F2026-08-15: -2.8 °F2026-08-16: -2.27 °F2026-08-17: -1.98 °F2026-08-18: -2.92 °F2026-08-19: -3.93 °F2026-08-20: -2.62 °F2026-08-21: -3.04 °F2026-08-22: -3.31 °F2026-08-23: -3.3 °F2026-08-24: -4.56 °F2026-08-25: -2.79 °F2026-08-26: -2.87 °F2026-08-27: -4.11 °F2026-08-28: -3.65 °F2026-08-29: -2.53 °F2026-08-30: -2.62 °F2026-08-052026-08-30°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 (26 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-2.62
2026-08-29-2.53
2026-08-28-3.65
2026-08-27-4.11
2026-08-26-2.87
2026-08-25-2.79
2026-08-24-4.56
2026-08-23-3.30
2026-08-22-3.31
2026-08-21-3.04
2026-08-20-2.62
2026-08-19-3.93
2026-08-18-2.92
2026-08-17-1.98
2026-08-16-2.27
2026-08-15-2.80
2026-08-14-3.64
2026-08-13-2.76
2026-08-12-4.33
2026-08-11-3.52
2026-08-10-2.22
2026-08-09-2.47
2026-08-08-2.83
2026-08-07-3.80
2026-08-06-3.54
2026-08-05-3.82

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at ALL, lead day 4-5 to -4.5 °F: 1 day-4.5 to -4 °F: 2 days-4 to -3.5 °F: 7 days-3.5 to -3 °F: 3 days-3 to -2.5 °F: 9 days-2.5 to -2 °F: 3 days-2 to -1.5 °F: 1 day-1.5 to -1 °F: 0 days-1 to -0.5 °F: 0 days-0.5 to 0 °F: 0 days0 to 0.5 °F: 0 days0.5 to 1 °F: 0 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| 2.98 · P90 |e| 4.02 °F-50+5 °Fn = 26 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
-5.00-4.501
-4.50-4.002
-4.00-3.507
-3.50-3.003
-3.00-2.509
-2.50-2.003
-2.00-1.501
-1.50-1.000
-1.00-0.500
-0.50+0.000
+0.00+0.500
+0.50+1.000
+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
2026-08263.16 -3.16

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26
ECMWF AIFS Single2026-08-05 → 2026-08-30 26

Compared with other models

Paired bootstrap on the days both models cover (90d, 00Z, bilinear, daily maximum). Negative means ECMWF AIFS Single has the lower MAE. "Distinguishable" means the 95 % interval excludes zero.

Other modelCommon days MAE difference °FDistinguishable
NCEP GFS 26 +0.42 [0.20, 0.68] yes
GraphCast (IFS init) 25 -1.62 [-1.90, -1.27] yes
ECMWF IFS HRES 20 +0.17 [-0.01, 0.53] no
Persistence (baseline) 26 -0.19 [-0.69, 0.25] no

Cite this page

ShortCastCheck, ALL aifs_single lead 4, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/ALL/model/aifs_single/lead/4/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: ALL (All stations (mean of daily station errors)), model aifs_single, lead day 4. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/ALL/model/aifs_single/lead/4/

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