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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 2

ALL · aifs_single · lead 2

Target day = initialization date + 2 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
tmax00Zbilinear30d28 2 QC3.62 [3.44, 3.82]0.55-3.16 [-3.43, -2.91]4.23 [4.05, 4.41]12% [9%, 15%]26%41%-0.10+0.492026-08-03 → 2026-08-30
tmax00Zbilinear90d28 2 QC3.62 [3.44, 3.85]0.55-3.16 [-3.45, -2.92]4.23 [4.06, 4.42]12% [9%, 15%]26%41%-0.10+0.492026-08-03 → 2026-08-30
tmax00Zbilinear365d28 2 QC3.62 [3.43, 3.86]0.55-3.16 [-3.48, -2.89]4.23 [4.06, 4.45]12% [9%, 15%]26%41%-0.10+0.492026-08-03 → 2026-08-30
tmax00Zbilinearall28 2 QC3.62 [3.42, 3.87]0.55-3.16 [-3.50, -2.90]4.23 [4.04, 4.44]12% [9%, 15%]26%41%-0.10+0.492026-08-03 → 2026-08-30
tmax00Znearest30d28 2 QC3.66 [3.45, 3.86]0.57-3.08 [-3.38, -2.81]4.29 [4.09, 4.48]12% [10%, 13%]27%41%-0.11+0.472026-08-03 → 2026-08-30
tmax00Znearest90d28 2 QC3.66 [3.46, 3.88]0.57-3.08 [-3.40, -2.80]4.29 [4.10, 4.50]12% [10%, 13%]27%41%-0.11+0.472026-08-03 → 2026-08-30
tmax00Znearest365d28 2 QC3.66 [3.45, 3.91]0.57-3.08 [-3.42, -2.79]4.29 [4.08, 4.53]12% [10%, 13%]27%41%-0.11+0.472026-08-03 → 2026-08-30
tmax00Znearestall28 2 QC3.66 [3.45, 3.91]0.57-3.08 [-3.45, -2.80]4.29 [4.08, 4.53]12% [10%, 13%]27%41%-0.11+0.472026-08-03 → 2026-08-30
tmax12Zbilinear30d28 2 QC3.63 [3.48, 3.78]0.48-3.30 [-3.49, -3.13]4.24 [4.09, 4.39]13% [11%, 15%]27%42%-0.10+0.562026-08-03 → 2026-08-30
tmax12Zbilinear90d28 2 QC3.63 [3.48, 3.80]0.48-3.30 [-3.52, -3.13]4.24 [4.09, 4.39]13% [11%, 15%]27%42%-0.10+0.562026-08-03 → 2026-08-30
tmax12Zbilinear365d28 2 QC3.63 [3.48, 3.82]0.48-3.30 [-3.52, -3.12]4.24 [4.09, 4.42]13% [11%, 15%]27%42%-0.10+0.562026-08-03 → 2026-08-30
tmax12Zbilinearall28 2 QC3.63 [3.48, 3.82]0.48-3.30 [-3.53, -3.12]4.24 [4.09, 4.42]13% [11%, 15%]27%42%-0.10+0.562026-08-03 → 2026-08-30
tmax12Znearest30d28 2 QC3.67 [3.51, 3.84]0.50-3.22 [-3.44, -3.01]4.30 [4.15, 4.47]14% [12%, 16%]27%41%-0.11+0.532026-08-03 → 2026-08-30
tmax12Znearest90d28 2 QC3.67 [3.52, 3.84]0.50-3.22 [-3.48, -3.02]4.30 [4.15, 4.47]14% [11%, 16%]27%41%-0.11+0.532026-08-03 → 2026-08-30
tmax12Znearest365d28 2 QC3.67 [3.51, 3.86]0.50-3.22 [-3.49, -3.00]4.30 [4.15, 4.49]14% [11%, 16%]27%41%-0.11+0.532026-08-03 → 2026-08-30
tmax12Znearestall28 2 QC3.67 [3.50, 3.87]0.50-3.22 [-3.48, -2.99]4.30 [4.15, 4.50]14% [11%, 16%]27%41%-0.11+0.532026-08-03 → 2026-08-30
tmin00Zbilinear30d28 2 QC2.34 [2.15, 2.51]0.47+0.34 [0.13, 0.55]3.02 [2.75, 3.25]30% [27%, 33%]52%72%+0.21+0.502026-08-03 → 2026-08-30
tmin00Zbilinear90d28 2 QC2.34 [2.15, 2.53]0.47+0.34 [0.10, 0.58]3.02 [2.75, 3.28]30% [26%, 34%]52%72%+0.21+0.502026-08-03 → 2026-08-30
tmin00Zbilinear365d28 2 QC2.34 [2.12, 2.56]0.47+0.34 [0.08, 0.59]3.02 [2.70, 3.29]30% [26%, 34%]52%72%+0.21+0.502026-08-03 → 2026-08-30
tmin00Zbilinearall28 2 QC2.34 [2.15, 2.56]0.47+0.34 [0.09, 0.58]3.02 [2.73, 3.31]30% [26%, 34%]52%72%+0.21+0.502026-08-03 → 2026-08-30
tmin00Znearest30d28 2 QC2.43 [2.22, 2.62]0.48+0.32 [0.09, 0.53]3.15 [2.85, 3.39]27% [23%, 32%]51%70%+0.18+0.492026-08-03 → 2026-08-30
tmin00Znearest90d28 2 QC2.43 [2.23, 2.63]0.48+0.32 [0.05, 0.56]3.15 [2.85, 3.42]27% [23%, 32%]51%70%+0.18+0.492026-08-03 → 2026-08-30
tmin00Znearest365d28 2 QC2.43 [2.19, 2.66]0.48+0.32 [0.02, 0.57]3.15 [2.81, 3.43]27% [22%, 32%]51%70%+0.18+0.492026-08-03 → 2026-08-30
tmin00Znearestall28 2 QC2.43 [2.22, 2.67]0.48+0.32 [0.05, 0.56]3.15 [2.83, 3.46]27% [23%, 32%]51%70%+0.18+0.492026-08-03 → 2026-08-30
tmin12Zbilinear30d28 2 QC2.24 [2.07, 2.41]0.39+0.30 [0.11, 0.47]2.91 [2.64, 3.15]31% [28%, 33%]54%72%+0.24+0.582026-08-03 → 2026-08-30
tmin12Zbilinear90d28 2 QC2.24 [2.06, 2.44]0.39+0.30 [0.06, 0.51]2.91 [2.64, 3.18]31% [27%, 34%]54%72%+0.24+0.582026-08-03 → 2026-08-30
tmin12Zbilinear365d28 2 QC2.24 [2.04, 2.47]0.39+0.30 [0.02, 0.51]2.91 [2.60, 3.21]31% [27%, 34%]54%72%+0.24+0.582026-08-03 → 2026-08-30
tmin12Zbilinearall28 2 QC2.24 [2.05, 2.47]0.39+0.30 [0.04, 0.50]2.91 [2.62, 3.22]31% [27%, 34%]54%72%+0.24+0.582026-08-03 → 2026-08-30
tmin12Znearest30d28 2 QC2.33 [2.15, 2.51]0.41+0.28 [0.07, 0.46]3.04 [2.75, 3.30]29% [26%, 32%]53%70%+0.21+0.562026-08-03 → 2026-08-30
tmin12Znearest90d28 2 QC2.33 [2.15, 2.55]0.41+0.28 [0.02, 0.50]3.04 [2.76, 3.35]29% [26%, 33%]53%70%+0.21+0.562026-08-03 → 2026-08-30
tmin12Znearest365d28 2 QC2.33 [2.13, 2.56]0.41+0.28 [-0.02, 0.50]3.04 [2.70, 3.35]29% [25%, 33%]53%70%+0.21+0.562026-08-03 → 2026-08-30
tmin12Znearestall28 2 QC2.33 [2.13, 2.57]0.41+0.28 [0.01, 0.48]3.04 [2.74, 3.39]29% [25%, 33%]53%70%+0.21+0.562026-08-03 → 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 2, 00Z bilinear tmax+5+2.50-2.5-52026-08-03: -3.98 °F2026-08-04: -3.06 °F2026-08-05: -3.78 °F2026-08-06: -2.54 °F2026-08-07: -3.65 °F2026-08-08: -3.03 °F2026-08-09: -2.55 °F2026-08-10: -2.55 °F2026-08-11: -2.54 °F2026-08-12: -3.91 °F2026-08-13: -2.77 °F2026-08-14: -3.71 °F2026-08-15: -2.16 °F2026-08-16: -1.79 °F2026-08-17: -2.75 °F2026-08-18: -2.86 °F2026-08-19: -2.98 °F2026-08-20: -3.69 °F2026-08-21: -3.67 °F2026-08-22: -4.12 °F2026-08-23: -3.9 °F2026-08-24: -3.82 °F2026-08-25: -2.66 °F2026-08-26: -2.82 °F2026-08-27: -3.55 °F2026-08-28: -3.83 °F2026-08-29: -2.96 °F2026-08-30: -2.92 °F2026-08-032026-08-30°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 (28 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-2.92
2026-08-29-2.96
2026-08-28-3.83
2026-08-27-3.55
2026-08-26-2.82
2026-08-25-2.66
2026-08-24-3.82
2026-08-23-3.90
2026-08-22-4.12
2026-08-21-3.67
2026-08-20-3.69
2026-08-19-2.98
2026-08-18-2.86
2026-08-17-2.75
2026-08-16-1.79
2026-08-15-2.16
2026-08-14-3.71
2026-08-13-2.77
2026-08-12-3.91
2026-08-11-2.54
2026-08-10-2.55
2026-08-09-2.55
2026-08-08-3.03
2026-08-07-3.65
2026-08-06-2.54
2026-08-05-3.78
2026-08-04-3.06
2026-08-03-3.98

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at ALL, lead day 2-5 to -4.5 °F: 0 days-4.5 to -4 °F: 1 day-4 to -3.5 °F: 11 days-3.5 to -3 °F: 2 days-3 to -2.5 °F: 12 days-2.5 to -2 °F: 1 day-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| 3.01 · P90 |e| 3.9 °F-50+5 °Fn = 28 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
-5.00-4.500
-4.50-4.001
-4.00-3.5011
-3.50-3.002
-3.00-2.5012
-2.50-2.001
-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
2026-08283.16 -3.16

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-03 → 2026-08-30 28
ECMWF AIFS Single2026-08-03 → 2026-08-30 28
ECMWF AIFS Single2026-08-03 → 2026-08-30 28
ECMWF AIFS Single2026-08-03 → 2026-08-30 28

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
Aurora (IFS init) 1 -1.88 [-1.88, -1.88] yes
FourCastNet v2 (IFS init) 1 -0.52 [-0.52, -0.52] yes
NCEP GFS 28 +0.55 [0.37, 0.69] yes
GraphCast (IFS init) 26 -1.50 [-1.69, -1.31] yes
ECMWF IFS HRES 23 +0.20 [-0.09, 0.49] no
Pangu-Weather (IFS init) 1 -0.90 [-0.90, -0.90] yes
Persistence (baseline) 28 +0.32 [-0.11, 0.59] no

Cite this page

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

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 2. 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/2/

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