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

All stations (mean of daily station errors) · ECMWF AIFS Single · lead day 8

ALL · aifs_single · lead 8

Target day = initialization date + 8 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
tmax00Zbilinear30d22 2 QC4.78 [4.29, 5.23]1.02-4.20 [-4.66, -3.61]6.10 [5.48, 6.64]11% [8%, 13%]24%37%-0.11+0.172026-08-09 → 2026-08-30
tmax00Zbilinear90d22 2 QC4.78 [4.16, 5.22]1.02-4.20 [-4.74, -3.47]6.10 [5.32, 6.63]11% [8%, 13%]24%37%-0.11+0.172026-08-09 → 2026-08-30
tmax00Zbilinear365d22 2 QC4.78 [4.17, 5.27]1.02-4.20 [-4.73, -3.50]6.10 [5.31, 6.67]11% [8%, 13%]24%37%-0.11+0.172026-08-09 → 2026-08-30
tmax00Zbilinearall22 2 QC4.78 [4.12, 5.31]1.02-4.20 [-4.74, -3.41]6.10 [5.24, 6.77]11% [8%, 13%]24%37%-0.11+0.172026-08-09 → 2026-08-30
tmax00Znearest30d22 2 QC4.80 [4.33, 5.25]1.02-4.16 [-4.60, -3.58]6.17 [5.56, 6.72]12% [10%, 16%]26%36%-0.12+0.172026-08-09 → 2026-08-30
tmax00Znearest90d22 2 QC4.80 [4.22, 5.24]1.02-4.16 [-4.65, -3.45]6.17 [5.41, 6.72]12% [9%, 17%]26%36%-0.12+0.172026-08-09 → 2026-08-30
tmax00Znearest365d22 2 QC4.80 [4.20, 5.32]1.02-4.16 [-4.65, -3.48]6.17 [5.39, 6.80]12% [9%, 17%]26%36%-0.12+0.172026-08-09 → 2026-08-30
tmax00Znearestall22 2 QC4.80 [4.16, 5.35]1.02-4.16 [-4.65, -3.39]6.17 [5.34, 6.86]12% [9%, 18%]26%36%-0.12+0.172026-08-09 → 2026-08-30
tmax12Zbilinear30d22 2 QC4.69 [4.39, 4.90]0.75-4.22 [-4.45, -3.89]5.82 [5.37, 6.13]13% [11%, 16%]21%34%-0.09+0.402026-08-09 → 2026-08-30
tmax12Zbilinear90d22 2 QC4.69 [4.33, 4.89]0.75-4.22 [-4.45, -3.84]5.82 [5.26, 6.11]13% [11%, 17%]21%34%-0.09+0.402026-08-09 → 2026-08-30
tmax12Zbilinear365d22 2 QC4.69 [4.30, 4.89]0.75-4.22 [-4.47, -3.86]5.82 [5.25, 6.13]13% [11%, 16%]21%34%-0.09+0.402026-08-09 → 2026-08-30
tmax12Zbilinearall22 2 QC4.69 [4.31, 4.91]0.75-4.22 [-4.46, -3.83]5.82 [5.25, 6.13]13% [11%, 16%]21%34%-0.09+0.402026-08-09 → 2026-08-30
tmax12Znearest30d22 2 QC4.71 [4.38, 4.95]0.75-4.17 [-4.39, -3.84]5.85 [5.40, 6.19]12% [10%, 14%]23%36%-0.10+0.392026-08-09 → 2026-08-30
tmax12Znearest90d22 2 QC4.71 [4.31, 4.94]0.75-4.17 [-4.40, -3.79]5.85 [5.27, 6.16]12% [10%, 14%]23%36%-0.10+0.392026-08-09 → 2026-08-30
tmax12Znearest365d22 2 QC4.71 [4.32, 4.96]0.75-4.17 [-4.42, -3.82]5.85 [5.29, 6.20]12% [10%, 14%]23%36%-0.10+0.392026-08-09 → 2026-08-30
tmax12Znearestall22 2 QC4.71 [4.29, 4.97]0.75-4.17 [-4.42, -3.79]5.85 [5.27, 6.21]12% [10%, 14%]23%36%-0.10+0.392026-08-09 → 2026-08-30
tmin00Zbilinear30d22 2 QC2.89 [2.52, 3.16]0.70+0.16 [-0.27, 0.65]3.75 [3.28, 4.08]24% [22%, 28%]45%64%+0.24+0.412026-08-09 → 2026-08-30
tmin00Zbilinear90d22 2 QC2.89 [2.48, 3.17]0.70+0.16 [-0.32, 0.66]3.75 [3.23, 4.11]24% [21%, 28%]45%64%+0.24+0.412026-08-09 → 2026-08-30
tmin00Zbilinear365d22 2 QC2.89 [2.48, 3.19]0.70+0.16 [-0.34, 0.74]3.75 [3.23, 4.12]24% [21%, 28%]45%64%+0.24+0.412026-08-09 → 2026-08-30
tmin00Zbilinearall22 2 QC2.89 [2.48, 3.19]0.70+0.16 [-0.36, 0.64]3.75 [3.23, 4.12]24% [21%, 28%]45%64%+0.24+0.412026-08-09 → 2026-08-30
tmin00Znearest30d22 2 QC2.96 [2.56, 3.26]0.71+0.13 [-0.31, 0.63]3.88 [3.37, 4.24]22% [20%, 25%]46%62%+0.22+0.402026-08-09 → 2026-08-30
tmin00Znearest90d22 2 QC2.96 [2.52, 3.28]0.71+0.13 [-0.37, 0.64]3.88 [3.32, 4.27]22% [19%, 26%]46%62%+0.22+0.402026-08-09 → 2026-08-30
tmin00Znearest365d22 2 QC2.96 [2.52, 3.29]0.71+0.13 [-0.38, 0.71]3.88 [3.33, 4.28]22% [19%, 26%]46%62%+0.22+0.402026-08-09 → 2026-08-30
tmin00Znearestall22 2 QC2.96 [2.51, 3.29]0.71+0.13 [-0.41, 0.61]3.88 [3.31, 4.29]22% [19%, 26%]46%62%+0.22+0.402026-08-09 → 2026-08-30
tmin12Zbilinear30d22 2 QC2.77 [2.49, 2.99]0.75+0.07 [-0.41, 0.51]3.61 [3.22, 3.92]24% [21%, 27%]46%64%+0.27+0.372026-08-09 → 2026-08-30
tmin12Zbilinear90d22 2 QC2.77 [2.47, 3.00]0.75+0.07 [-0.54, 0.59]3.61 [3.19, 3.95]24% [21%, 27%]46%64%+0.27+0.372026-08-09 → 2026-08-30
tmin12Zbilinear365d22 2 QC2.77 [2.45, 3.00]0.75+0.07 [-0.54, 0.62]3.61 [3.17, 3.95]24% [21%, 27%]46%64%+0.27+0.372026-08-09 → 2026-08-30
tmin12Zbilinearall22 2 QC2.77 [2.45, 3.01]0.75+0.07 [-0.59, 0.55]3.61 [3.17, 3.95]24% [21%, 27%]46%64%+0.27+0.372026-08-09 → 2026-08-30
tmin12Znearest30d22 2 QC2.87 [2.56, 3.12]0.76+0.05 [-0.44, 0.50]3.74 [3.32, 4.07]24% [21%, 26%]46%62%+0.24+0.362026-08-09 → 2026-08-30
tmin12Znearest90d22 2 QC2.87 [2.53, 3.13]0.76+0.05 [-0.58, 0.59]3.74 [3.28, 4.10]24% [20%, 27%]46%62%+0.24+0.362026-08-09 → 2026-08-30
tmin12Znearest365d22 2 QC2.87 [2.51, 3.13]0.76+0.05 [-0.58, 0.60]3.74 [3.26, 4.10]24% [20%, 27%]46%62%+0.24+0.362026-08-09 → 2026-08-30
tmin12Znearestall22 2 QC2.87 [2.51, 3.15]0.76+0.05 [-0.63, 0.54]3.74 [3.26, 4.10]24% [21%, 27%]46%62%+0.24+0.362026-08-09 → 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 8, 00Z bilinear tmax+10+50-5-102026-08-09: -5.04 °F2026-08-10: -4.67 °F2026-08-11: -4.08 °F2026-08-12: -6.68 °F2026-08-13: -3.16 °F2026-08-14: -5.69 °F2026-08-15: -3.85 °F2026-08-16: -3.66 °F2026-08-17: -4.67 °F2026-08-18: -3.35 °F2026-08-19: -3.06 °F2026-08-20: -3.46 °F2026-08-21: -4.05 °F2026-08-22: -2.27 °F2026-08-23: -5.2 °F2026-08-24: -7.44 °F2026-08-25: -5.42 °F2026-08-26: -4.05 °F2026-08-27: -2.8 °F2026-08-28: -3.17 °F2026-08-29: -4.26 °F2026-08-30: -2.44 °F2026-08-092026-08-30°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 (22 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-2.44
2026-08-29-4.26
2026-08-28-3.17
2026-08-27-2.80
2026-08-26-4.05
2026-08-25-5.42
2026-08-24-7.44
2026-08-23-5.20
2026-08-22-2.27
2026-08-21-4.05
2026-08-20-3.46
2026-08-19-3.06
2026-08-18-3.35
2026-08-17-4.67
2026-08-16-3.66
2026-08-15-3.85
2026-08-14-5.69
2026-08-13-3.16
2026-08-12-6.68
2026-08-11-4.08
2026-08-10-4.67
2026-08-09-5.04

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at ALL, lead day 8-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 1 day-7 to -6 °F: 1 day-6 to -5 °F: 4 days-5 to -4 °F: 6 days-4 to -3 °F: 7 days-3 to -2 °F: 3 days-2 to -1 °F: 0 days-1 to 0 °F: 0 days0 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| 4.05 · P90 |e| 5.66 °F-100+10 °Fn = 22 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
-8.00-7.001
-7.00-6.001
-6.00-5.004
-5.00-4.006
-4.00-3.007
-3.00-2.003
-2.00-1.000
-1.00+0.000
+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
2026-08224.20 -4.20

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22
ECMWF AIFS Single2026-08-09 → 2026-08-30 22

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 22 +0.45 [-0.09, 0.91] no
GraphCast (IFS init) 22 -1.62 [-2.26, -0.89] yes
ECMWF IFS HRES 17 +0.37 [-0.46, 1.35] no
Persistence (baseline) 22 +0.49 [-0.25, 1.09] no

Cite this page

ShortCastCheck, ALL aifs_single lead 8, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/ALL/model/aifs_single/lead/8/

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 8. 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/8/

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