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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 9

ALL · aifs_single · 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, 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
tmax00Zbilinear30d21 2 QC5.01 [4.50, 5.42]1.46-4.10 [-5.13, -3.19]6.06 [5.46, 6.57]7% [4%, 12%]19%33%-0.16-0.352026-08-10 → 2026-08-30
tmax00Zbilinear90d21 2 QC5.01 [4.26, 5.41]1.46-4.10 [-5.20, -3.07]6.06 [5.14, 6.61]7% [4%, 14%]19%33%-0.16-0.352026-08-10 → 2026-08-30
tmax00Zbilinear365d21 2 QC5.01 [4.29, 5.44]1.46-4.10 [-5.26, -3.03]6.06 [5.22, 6.63]7% [4%, 13%]19%33%-0.16-0.352026-08-10 → 2026-08-30
tmax00Zbilinearall21 2 QC5.01 [4.29, 5.46]1.46-4.10 [-5.33, -3.01]6.06 [5.17, 6.63]7% [4%, 14%]19%33%-0.16-0.352026-08-10 → 2026-08-30
tmax00Znearest30d21 2 QC5.06 [4.55, 5.45]1.45-4.10 [-5.13, -3.20]6.11 [5.50, 6.59]7% [5%, 10%]19%32%-0.17-0.342026-08-10 → 2026-08-30
tmax00Znearest90d21 2 QC5.06 [4.30, 5.44]1.45-4.10 [-5.20, -3.09]6.11 [5.19, 6.62]7% [5%, 12%]19%32%-0.17-0.342026-08-10 → 2026-08-30
tmax00Znearest365d21 2 QC5.06 [4.34, 5.46]1.45-4.10 [-5.26, -3.05]6.11 [5.23, 6.65]7% [5%, 11%]19%32%-0.17-0.342026-08-10 → 2026-08-30
tmax00Znearestall21 2 QC5.06 [4.34, 5.49]1.45-4.10 [-5.32, -3.02]6.11 [5.22, 6.66]7% [5%, 11%]19%32%-0.17-0.342026-08-10 → 2026-08-30
tmax12Zbilinear30d21 2 QC5.16 [4.81, 5.41]0.84-4.70 [-4.96, -4.35]6.40 [6.00, 6.69]13% [10%, 17%]22%31%-0.19+0.222026-08-10 → 2026-08-30
tmax12Zbilinear90d21 2 QC5.16 [4.71, 5.40]0.84-4.70 [-4.95, -4.26]6.40 [5.85, 6.68]13% [10%, 18%]22%31%-0.19+0.222026-08-10 → 2026-08-30
tmax12Zbilinear365d21 2 QC5.16 [4.72, 5.42]0.84-4.70 [-4.97, -4.26]6.40 [5.92, 6.69]13% [10%, 17%]22%31%-0.19+0.222026-08-10 → 2026-08-30
tmax12Zbilinearall21 2 QC5.16 [4.71, 5.42]0.84-4.70 [-4.97, -4.26]6.40 [5.90, 6.71]13% [10%, 17%]22%31%-0.19+0.222026-08-10 → 2026-08-30
tmax12Znearest30d21 2 QC5.18 [4.85, 5.42]0.84-4.66 [-4.93, -4.32]6.44 [6.01, 6.74]13% [11%, 16%]22%33%-0.20+0.222026-08-10 → 2026-08-30
tmax12Znearest90d21 2 QC5.18 [4.76, 5.41]0.84-4.66 [-4.92, -4.22]6.44 [5.89, 6.74]13% [11%, 16%]22%33%-0.20+0.222026-08-10 → 2026-08-30
tmax12Znearest365d21 2 QC5.18 [4.78, 5.42]0.84-4.66 [-4.95, -4.25]6.44 [5.91, 6.76]13% [11%, 16%]22%33%-0.20+0.222026-08-10 → 2026-08-30
tmax12Znearestall21 2 QC5.18 [4.78, 5.43]0.84-4.66 [-4.96, -4.26]6.44 [5.91, 6.76]13% [11%, 16%]22%33%-0.20+0.222026-08-10 → 2026-08-30
tmin00Zbilinear30d21 2 QC3.40 [2.76, 3.95]1.63+0.93 [-0.10, 1.85]4.39 [3.66, 5.00]21% [17%, 24%]37%52%+0.11-0.422026-08-10 → 2026-08-30
tmin00Zbilinear90d21 2 QC3.40 [2.75, 4.00]1.63+0.93 [-0.18, 1.96]4.39 [3.63, 5.01]21% [17%, 25%]37%52%+0.11-0.422026-08-10 → 2026-08-30
tmin00Zbilinear365d21 2 QC3.40 [2.72, 4.00]1.63+0.93 [-0.21, 1.99]4.39 [3.58, 5.05]21% [17%, 25%]37%52%+0.11-0.422026-08-10 → 2026-08-30
tmin00Zbilinearall21 2 QC3.40 [2.73, 4.05]1.63+0.93 [-0.20, 1.97]4.39 [3.58, 5.12]21% [17%, 25%]37%52%+0.11-0.422026-08-10 → 2026-08-30
tmin00Znearest30d21 2 QC3.45 [2.80, 4.02]1.62+0.91 [-0.10, 1.83]4.45 [3.73, 5.06]20% [16%, 23%]37%51%+0.10-0.412026-08-10 → 2026-08-30
tmin00Znearest90d21 2 QC3.45 [2.78, 4.06]1.62+0.91 [-0.16, 1.94]4.45 [3.70, 5.06]20% [15%, 23%]37%51%+0.10-0.412026-08-10 → 2026-08-30
tmin00Znearest365d21 2 QC3.45 [2.75, 4.07]1.62+0.91 [-0.20, 1.97]4.45 [3.63, 5.10]20% [15%, 23%]37%51%+0.10-0.412026-08-10 → 2026-08-30
tmin00Znearestall21 2 QC3.45 [2.75, 4.09]1.62+0.91 [-0.19, 1.94]4.45 [3.63, 5.16]20% [15%, 23%]37%51%+0.10-0.412026-08-10 → 2026-08-30
tmin12Zbilinear30d21 2 QC3.01 [2.66, 3.31]0.93-0.19 [-0.99, 0.57]4.04 [3.57, 4.38]22% [19%, 25%]46%63%+0.21+0.182026-08-10 → 2026-08-30
tmin12Zbilinear90d21 2 QC3.01 [2.60, 3.35]0.93-0.19 [-1.14, 0.67]4.04 [3.49, 4.39]22% [19%, 25%]46%63%+0.21+0.182026-08-10 → 2026-08-30
tmin12Zbilinear365d21 2 QC3.01 [2.59, 3.36]0.93-0.19 [-1.18, 0.72]4.04 [3.46, 4.40]22% [19%, 25%]46%63%+0.21+0.182026-08-10 → 2026-08-30
tmin12Zbilinearall21 2 QC3.01 [2.60, 3.35]0.93-0.19 [-1.27, 0.59]4.04 [3.48, 4.40]22% [19%, 25%]46%63%+0.21+0.182026-08-10 → 2026-08-30
tmin12Znearest30d21 2 QC3.10 [2.72, 3.41]0.94-0.21 [-1.02, 0.54]4.15 [3.67, 4.50]21% [19%, 24%]45%62%+0.19+0.182026-08-10 → 2026-08-30
tmin12Znearest90d21 2 QC3.10 [2.65, 3.45]0.94-0.21 [-1.17, 0.65]4.15 [3.57, 4.51]21% [19%, 25%]45%62%+0.19+0.182026-08-10 → 2026-08-30
tmin12Znearest365d21 2 QC3.10 [2.63, 3.45]0.94-0.21 [-1.22, 0.69]4.15 [3.55, 4.52]21% [19%, 24%]45%62%+0.19+0.182026-08-10 → 2026-08-30
tmin12Znearestall21 2 QC3.10 [2.64, 3.46]0.94-0.21 [-1.30, 0.56]4.15 [3.57, 4.52]21% [19%, 25%]45%62%+0.19+0.182026-08-10 → 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 ECMWF AIFS Single at ALL, lead day 9, 00Z bilinear tmax+10+50-5-102026-08-10: -2.8 °F2026-08-11: -6.55 °F2026-08-12: -5.06 °F2026-08-13: -5.58 °F2026-08-14: -4.62 °F2026-08-15: -5.57 °F2026-08-16: -5.51 °F2026-08-17: -6.62 °F2026-08-18: -4.46 °F2026-08-19: -5.9 °F2026-08-20: -2.35 °F2026-08-21: -0.52 °F2026-08-22: -4.55 °F2026-08-23: -2.6 °F2026-08-24: -3.82 °F2026-08-25: -5.15 °F2026-08-26: -2.1 °F2026-08-27: -1.63 °F2026-08-28: -4.07 °F2026-08-29: -1.71 °F2026-08-30: -4.89 °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
2026-08-30-4.89
2026-08-29-1.71
2026-08-28-4.07
2026-08-27-1.63
2026-08-26-2.10
2026-08-25-5.15
2026-08-24-3.82
2026-08-23-2.60
2026-08-22-4.55
2026-08-21-0.52
2026-08-20-2.35
2026-08-19-5.90
2026-08-18-4.46
2026-08-17-6.62
2026-08-16-5.51
2026-08-15-5.57
2026-08-14-4.62
2026-08-13-5.58
2026-08-12-5.06
2026-08-11-6.55
2026-08-10-2.80

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at ALL, lead day 9-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 2 days-6 to -5 °F: 6 days-5 to -4 °F: 5 days-4 to -3 °F: 1 day-3 to -2 °F: 4 days-2 to -1 °F: 2 days-1 to 0 °F: 1 day0 to 1 °F: 0 days1 to 2 °F: 0 days2 to 3 °F: 0 days3 to 4 °F: 0 days4 to 5 °F: 0 days5 to 6 °F: 0 days6 to 7 °F: 0 days7 to 8 °F: 0 days8 to 9 °F: 0 days9 to 10 °F: 0 daysdashed: P50 |e| 4.55 · P90 |e| 5.9 °F-100+10 °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
-10.00-9.000
-9.00-8.000
-8.00-7.000
-7.00-6.002
-6.00-5.006
-5.00-4.005
-4.00-3.001
-3.00-2.004
-2.00-1.002
-1.00+0.001
+0.00+1.000
+1.00+2.000
+2.00+3.000
+3.00+4.000
+4.00+5.000
+5.00+6.000
+6.00+7.000
+7.00+8.000
+8.00+9.000
+9.00+10.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08214.10 -4.10

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-10 → 2026-08-30 21
ECMWF AIFS Single2026-08-10 → 2026-08-30 21
ECMWF AIFS Single2026-08-10 → 2026-08-30 21
ECMWF AIFS Single2026-08-10 → 2026-08-30 21

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
NCEP GFS 21 +0.34 [-0.29, 0.97] no
GraphCast (IFS init) 21 -1.12 [-2.09, -0.53] yes
ECMWF IFS HRES 16 +0.60 [-0.60, 1.19] no
Persistence (baseline) 21 +0.68 [0.12, 1.35] yes

Cite this page

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

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 9. 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/9/

Accessed2026-08-31 (data through 2026-08-30; page built 2026-08-31T03:52:06+00:00)

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