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

All stations (mean of daily station errors) · GraphCast (IFS init) · lead day 1

ALL · graphcast_ifs · lead 1

Target day = initialization date + 1 day. 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, GRAP_v100, starting 2026-01-01 — 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
tmax00Zbilinear30d27 2 QC4.91 [4.75, 5.08]0.40-4.84 [-5.03, -4.66]5.43 [5.26, 5.59]5% [4%, 7%]12%22%-0.84+0.452026-08-02 → 2026-08-30
tmax00Zbilinear90d27 2 QC4.91 [4.73, 5.12]0.40-4.84 [-5.07, -4.65]5.43 [5.26, 5.63]5% [4%, 7%]12%22%-0.84+0.452026-08-02 → 2026-08-30
tmax00Zbilinear365d33 2 QC4.87 [4.72, 5.06]0.42-4.79 [-5.00, -4.63]5.46 [5.30, 5.64]6% [4%, 8%]13%25%-0.60+0.592026-01-02 → 2026-08-30
tmax00Zbilinearall33 2 QC4.87 [4.71, 5.05]0.42-4.79 [-4.99, -4.61]5.46 [5.29, 5.64]6% [4%, 8%]13%25%-0.60+0.592026-01-02 → 2026-08-30
tmax00Znearest30d27 2 QC5.10 [4.97, 5.25]0.42-4.77 [-4.99, -4.55]5.66 [5.51, 5.84]6% [4%, 8%]13%21%-0.91+0.432026-08-02 → 2026-08-30
tmax00Znearest90d27 2 QC5.10 [4.96, 5.29]0.42-4.77 [-5.05, -4.53]5.66 [5.49, 5.89]6% [4%, 8%]13%21%-0.91+0.432026-08-02 → 2026-08-30
tmax00Znearest365d33 2 QC5.04 [4.88, 5.23]0.44-4.75 [-4.99, -4.56]5.66 [5.51, 5.86]7% [5%, 9%]15%23%-0.66+0.582026-01-02 → 2026-08-30
tmax00Znearestall33 2 QC5.04 [4.88, 5.22]0.44-4.75 [-4.99, -4.54]5.66 [5.51, 5.86]7% [5%, 9%]15%23%-0.66+0.582026-01-02 → 2026-08-30
tmax12Zbilinear30d27 2 QC5.28 [5.07, 5.50]0.36-5.22 [-5.44, -5.01]5.87 [5.62, 6.09]6% [4%, 7%]12%20%-0.98+0.502026-08-02 → 2026-08-30
tmax12Zbilinear90d27 2 QC5.28 [5.05, 5.54]0.36-5.22 [-5.49, -4.98]5.87 [5.58, 6.14]6% [4%, 7%]12%20%-0.98+0.502026-08-02 → 2026-08-30
tmax12Zbilinear365d32 2 QC5.22 [5.01, 5.48]0.38-5.16 [-5.42, -4.95]5.86 [5.64, 6.08]6% [5%, 7%]14%21%-0.74+0.612026-01-02 → 2026-08-30
tmax12Zbilinearall32 2 QC5.22 [5.01, 5.48]0.38-5.16 [-5.43, -4.94]5.86 [5.64, 6.10]6% [4%, 7%]14%21%-0.74+0.612026-01-02 → 2026-08-30
tmax12Znearest30d27 2 QC5.43 [5.24, 5.65]0.39-5.12 [-5.39, -4.85]6.04 [5.79, 6.31]6% [4%, 8%]12%20%-1.03+0.462026-08-02 → 2026-08-30
tmax12Znearest90d27 2 QC5.43 [5.20, 5.70]0.39-5.12 [-5.46, -4.81]6.04 [5.74, 6.38]6% [3%, 8%]12%20%-1.03+0.462026-08-02 → 2026-08-30
tmax12Znearest365d32 2 QC5.36 [5.14, 5.63]0.40-5.09 [-5.40, -4.84]6.03 [5.78, 6.32]7% [4%, 9%]13%21%-0.79+0.592026-01-02 → 2026-08-30
tmax12Znearestall32 2 QC5.36 [5.14, 5.63]0.40-5.09 [-5.39, -4.83]6.03 [5.79, 6.32]7% [4%, 9%]13%21%-0.79+0.592026-01-02 → 2026-08-30
tmin00Zbilinear30d27 2 QC2.09 [1.95, 2.24]0.56+0.71 [0.47, 0.96]2.79 [2.53, 3.01]35% [33%, 38%]59%73%+0.10+0.222026-08-02 → 2026-08-30
tmin00Zbilinear90d27 2 QC2.09 [1.96, 2.28]0.56+0.71 [0.43, 0.95]2.79 [2.54, 3.06]35% [33%, 39%]59%73%+0.10+0.222026-08-02 → 2026-08-30
tmin00Zbilinear365d33 2 QC2.23 [2.01, 2.56]0.62+0.80 [0.53, 1.06]3.07 [2.65, 3.60]34% [30%, 37%]57%72%+0.19+0.362026-01-02 → 2026-08-30
tmin00Zbilinearall33 2 QC2.23 [2.02, 2.55]0.62+0.80 [0.50, 1.05]3.07 [2.65, 3.59]34% [31%, 38%]57%72%+0.19+0.362026-01-02 → 2026-08-30
tmin00Znearest30d27 2 QC2.12 [1.92, 2.28]0.56+0.72 [0.49, 0.95]2.87 [2.56, 3.11]37% [33%, 39%]60%72%+0.09+0.232026-08-02 → 2026-08-30
tmin00Znearest90d27 2 QC2.12 [1.94, 2.32]0.56+0.72 [0.43, 0.95]2.87 [2.57, 3.16]37% [33%, 39%]60%72%+0.09+0.232026-08-02 → 2026-08-30
tmin00Znearest365d33 2 QC2.28 [2.01, 2.64]0.62+0.80 [0.55, 1.03]3.13 [2.71, 3.65]34% [28%, 39%]57%71%+0.17+0.362026-01-02 → 2026-08-30
tmin00Znearestall33 2 QC2.28 [2.00, 2.64]0.62+0.80 [0.50, 1.03]3.13 [2.69, 3.64]34% [27%, 38%]57%71%+0.17+0.362026-01-02 → 2026-08-30
tmin12Zbilinear30d27 2 QC1.99 [1.85, 2.14]0.52+0.30 [0.09, 0.48]2.66 [2.41, 2.87]35% [33%, 37%]61%76%+0.14+0.282026-08-02 → 2026-08-30
tmin12Zbilinear90d27 2 QC1.99 [1.86, 2.18]0.52+0.30 [0.04, 0.48]2.66 [2.43, 2.92]35% [33%, 37%]61%76%+0.14+0.282026-08-02 → 2026-08-30
tmin12Zbilinear365d32 2 QC2.10 [1.90, 2.40]0.57+0.39 [0.14, 0.65]2.86 [2.52, 3.31]34% [31%, 36%]59%75%+0.23+0.422026-01-02 → 2026-08-30
tmin12Zbilinearall32 2 QC2.10 [1.91, 2.38]0.57+0.39 [0.11, 0.65]2.86 [2.52, 3.32]34% [31%, 36%]59%75%+0.23+0.422026-01-02 → 2026-08-30
tmin12Znearest30d27 2 QC2.07 [1.87, 2.23]0.53+0.34 [0.12, 0.53]2.77 [2.48, 3.00]36% [32%, 39%]61%76%+0.11+0.272026-08-02 → 2026-08-30
tmin12Znearest90d27 2 QC2.07 [1.88, 2.26]0.53+0.34 [0.07, 0.53]2.77 [2.51, 3.05]36% [32%, 39%]61%76%+0.11+0.272026-08-02 → 2026-08-30
tmin12Znearest365d32 2 QC2.18 [1.93, 2.49]0.56+0.42 [0.19, 0.65]2.96 [2.60, 3.40]34% [29%, 38%]59%74%+0.20+0.422026-01-02 → 2026-08-30
tmin12Znearestall32 2 QC2.18 [1.94, 2.50]0.56+0.42 [0.15, 0.66]2.96 [2.60, 3.40]34% [29%, 38%]59%74%+0.20+0.422026-01-02 → 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 GraphCast (IFS init) at ALL, lead day 1, 00Z bilinear tmax+10+50-5-102026-08-02: -4.7 °F2026-08-03: -5.42 °F2026-08-04: -4.58 °F2026-08-05: -5.38 °F2026-08-06: -4.67 °F2026-08-07: -4.35 °F2026-08-08: -4.04 °F2026-08-09: -4.02 °F2026-08-10: -4.17 °F2026-08-11: -4.57 °F2026-08-12: -5.94 °F2026-08-13: -4.71 °F2026-08-14: -5.41 °F2026-08-15: -4.64 °F2026-08-16: -4.59 °F2026-08-17: -4.93 °F2026-08-18: -4.57 °F2026-08-19: -4.84 °F2026-08-20: -5.16 °F2026-08-21: -4.51 °F2026-08-22: -4.29 °F2026-08-23: -5.16 °F2026-08-24: -5.31 °F2026-08-25: -4.72 °F2026-08-26: -5.1 °F2026-08-29: -5.58 °F2026-08-30: -5.27 °F2026-08-022026-08-30°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 (29 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-5.27
2026-08-29-5.58
2026-08-28—
2026-08-27—
2026-08-26-5.10
2026-08-25-4.72
2026-08-24-5.31
2026-08-23-5.16
2026-08-22-4.29
2026-08-21-4.51
2026-08-20-5.16
2026-08-19-4.84
2026-08-18-4.57
2026-08-17-4.93
2026-08-16-4.59
2026-08-15-4.64
2026-08-14-5.41
2026-08-13-4.71
2026-08-12-5.94
2026-08-11-4.57
2026-08-10-4.17
2026-08-09-4.02
2026-08-08-4.04
2026-08-07-4.35
2026-08-06-4.67
2026-08-05-5.38
2026-08-04-4.58
2026-08-03-5.42
2026-08-02-4.70

Error distribution

Distribution of the signed daily error in °F for GraphCast (IFS init) at ALL, lead day 1-10 to -9 °F: 0 days-9 to -8 °F: 0 days-8 to -7 °F: 0 days-7 to -6 °F: 0 days-6 to -5 °F: 13 days-5 to -4 °F: 18 days-4 to -3 °F: 2 days-3 to -2 °F: 0 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| 4.71 · P90 |e| 5.4 °F-100+10 °Fn = 33 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
-7.00-6.000
-6.00-5.0013
-5.00-4.0018
-4.00-3.002
-3.00-2.000
-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
2026-08274.84 -4.84
2026-0164.58 -4.58

Availability

ModelScored period DaysCoverage
GraphCast (IFS init)2026-01-02 → 2026-08-30 33
GraphCast (IFS init)2026-01-02 → 2026-08-30 33
GraphCast (IFS init)2026-01-02 → 2026-08-30 32
GraphCast (IFS init)2026-01-02 → 2026-08-30 32

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 27 +1.50 [1.39, 1.65] yes
Aurora (GFS init) 1 -1.03 [-1.03, -1.03] yes
Aurora (IFS init) 2 +0.15 [0.10, 0.20] yes
FourCastNet v2 (GFS init) 1 +1.37 [1.37, 1.37] yes
FourCastNet v2 (IFS init) 2 +1.42 [1.25, 1.60] yes
NCEP GFS 27 +2.00 [1.87, 2.17] yes
GraphCast (GFS init) 1 -0.68 [-0.68, -0.68] yes
ECMWF IFS HRES 21 +1.45 [1.29, 1.60] yes
Pangu-Weather (GFS init) 1 +1.76 [1.76, 1.76] yes
Pangu-Weather (IFS init) 2 +1.34 [1.16, 1.52] yes
Persistence (baseline) 27 +2.24 [2.02, 2.47] yes

Cite this page

ShortCastCheck, ALL graphcast_ifs lead 1, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/ALL/model/graphcast_ifs/lead/1/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: ALL (All stations (mean of daily station errors)), model graphcast_ifs, lead day 1. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/ALL/model/graphcast_ifs/lead/1/

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

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