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

San Francisco Intl · ECMWF AIFS Single · lead day 2

KSFO · 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, 1 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 1 QC4.58 [3.75, 5.61]2.68-4.29 [-5.47, -3.40]5.32 [4.41, 6.25]14% [0%, 31%]25%32%-0.15+0.332026-08-03 → 2026-08-30
tmax00Zbilinear90d28 1 QC4.58 [3.70, 5.74]2.68-4.29 [-5.58, -3.32]5.32 [4.38, 6.30]14% [0%, 33%]25%32%-0.15+0.332026-08-03 → 2026-08-30
tmax00Zbilinear365d28 1 QC4.58 [3.70, 5.80]2.68-4.29 [-5.72, -3.30]5.32 [4.31, 6.44]14% [0%, 32%]25%32%-0.15+0.332026-08-03 → 2026-08-30
tmax00Zbilinearall28 1 QC4.58 [3.77, 5.82]2.68-4.29 [-5.78, -3.35]5.32 [4.41, 6.35]14% [0%, 33%]25%32%-0.15+0.332026-08-03 → 2026-08-30
tmax00Znearest30d28 1 QC2.84 [1.99, 3.65]2.73-0.62 [-1.99, 0.56]3.47 [2.69, 4.13]29% [13%, 52%]43%46%+0.29+0.322026-08-03 → 2026-08-30
tmax00Znearest90d28 1 QC2.84 [1.81, 3.75]2.73-0.62 [-2.10, 0.69]3.47 [2.53, 4.18]29% [11%, 57%]43%46%+0.29+0.322026-08-03 → 2026-08-30
tmax00Znearest365d28 1 QC2.84 [1.77, 3.87]2.73-0.62 [-2.34, 0.75]3.47 [2.50, 4.29]29% [9%, 56%]43%46%+0.29+0.322026-08-03 → 2026-08-30
tmax00Znearestall28 1 QC2.84 [1.75, 3.84]2.73-0.62 [-2.30, 0.68]3.47 [2.50, 4.23]29% [9%, 60%]43%46%+0.29+0.322026-08-03 → 2026-08-30
tmax12Zbilinear30d28 1 QC4.46 [3.49, 5.65]2.75-4.33 [-5.60, -3.34]5.35 [4.36, 6.35]21% [10%, 30%]29%36%-0.12+0.322026-08-03 → 2026-08-30
tmax12Zbilinear90d28 1 QC4.46 [3.44, 5.79]2.75-4.33 [-5.72, -3.25]5.35 [4.31, 6.43]21% [7%, 29%]29%36%-0.12+0.322026-08-03 → 2026-08-30
tmax12Zbilinear365d28 1 QC4.46 [3.41, 5.91]2.75-4.33 [-5.85, -3.27]5.35 [4.22, 6.57]21% [9%, 29%]29%36%-0.12+0.322026-08-03 → 2026-08-30
tmax12Zbilinearall28 1 QC4.46 [3.46, 6.02]2.75-4.33 [-5.97, -3.32]5.35 [4.35, 6.52]21% [6%, 29%]29%36%-0.12+0.322026-08-03 → 2026-08-30
tmax12Znearest30d28 1 QC2.83 [1.98, 3.63]2.73-0.59 [-2.05, 0.57]3.43 [2.58, 4.17]25% [7%, 43%]39%50%+0.29+0.322026-08-03 → 2026-08-30
tmax12Znearest90d28 1 QC2.83 [1.85, 3.72]2.73-0.59 [-2.15, 0.61]3.43 [2.46, 4.23]25% [0%, 48%]39%50%+0.29+0.322026-08-03 → 2026-08-30
tmax12Znearest365d28 1 QC2.83 [1.79, 3.86]2.73-0.59 [-2.38, 0.63]3.43 [2.42, 4.32]25% [0%, 50%]39%50%+0.29+0.322026-08-03 → 2026-08-30
tmax12Znearestall28 1 QC2.83 [1.84, 3.79]2.73-0.59 [-2.28, 0.57]3.43 [2.41, 4.26]25% [0%, 47%]39%50%+0.29+0.322026-08-03 → 2026-08-30
tmin00Zbilinear30d28 1 QC1.05 [0.80, 1.34]0.91-0.50 [-0.92, 0.00]1.30 [1.05, 1.53]46% [29%, 62%]86%100%+0.05+0.182026-08-03 → 2026-08-30
tmin00Zbilinear90d28 1 QC1.05 [0.78, 1.37]0.91-0.50 [-0.97, 0.04]1.30 [1.00, 1.55]46% [26%, 63%]86%100%+0.05+0.182026-08-03 → 2026-08-30
tmin00Zbilinear365d28 1 QC1.05 [0.77, 1.36]0.91-0.50 [-0.95, 0.05]1.30 [1.01, 1.56]46% [25%, 64%]86%100%+0.05+0.182026-08-03 → 2026-08-30
tmin00Zbilinearall28 1 QC1.05 [0.75, 1.39]0.91-0.50 [-1.03, 0.03]1.30 [1.00, 1.57]46% [23%, 64%]86%100%+0.05+0.182026-08-03 → 2026-08-30
tmin00Znearest30d28 1 QC1.15 [0.81, 1.52]1.14-0.17 [-0.73, 0.40]1.43 [1.06, 1.76]50% [29%, 75%]79%96%-0.04-0.032026-08-03 → 2026-08-30
tmin00Znearest90d28 1 QC1.15 [0.72, 1.56]1.14-0.17 [-0.77, 0.42]1.43 [0.92, 1.80]50% [26%, 85%]79%96%-0.04-0.032026-08-03 → 2026-08-30
tmin00Znearest365d28 1 QC1.15 [0.73, 1.57]1.14-0.17 [-0.78, 0.46]1.43 [0.95, 1.83]50% [25%, 81%]79%96%-0.04-0.032026-08-03 → 2026-08-30
tmin00Znearestall28 1 QC1.15 [0.73, 1.56]1.14-0.17 [-0.81, 0.43]1.43 [0.95, 1.82]50% [24%, 85%]79%96%-0.04-0.032026-08-03 → 2026-08-30
tmin12Zbilinear30d28 1 QC1.10 [0.83, 1.41]0.90-0.57 [-0.99, -0.06]1.32 [1.03, 1.60]50% [30%, 69%]86%100%+0.00+0.192026-08-03 → 2026-08-30
tmin12Zbilinear90d28 1 QC1.10 [0.80, 1.47]0.90-0.57 [-1.04, -0.05]1.32 [0.97, 1.63]50% [26%, 72%]86%100%+0.00+0.192026-08-03 → 2026-08-30
tmin12Zbilinear365d28 1 QC1.10 [0.81, 1.47]0.90-0.57 [-1.01, -0.03]1.32 [0.98, 1.64]50% [27%, 71%]86%100%+0.00+0.192026-08-03 → 2026-08-30
tmin12Zbilinearall28 1 QC1.10 [0.78, 1.46]0.90-0.57 [-1.08, -0.05]1.32 [0.97, 1.64]50% [25%, 71%]86%100%+0.00+0.192026-08-03 → 2026-08-30
tmin12Znearest30d28 1 QC1.14 [0.75, 1.55]1.15-0.19 [-0.71, 0.36]1.45 [1.03, 1.82]50% [30%, 74%]79%96%-0.03-0.042026-08-03 → 2026-08-30
tmin12Znearest90d28 1 QC1.14 [0.64, 1.62]1.15-0.19 [-0.78, 0.37]1.45 [0.86, 1.88]50% [29%, 80%]79%96%-0.03-0.042026-08-03 → 2026-08-30
tmin12Znearest365d28 1 QC1.14 [0.65, 1.67]1.15-0.19 [-0.80, 0.40]1.45 [0.86, 1.90]50% [29%, 79%]79%96%-0.03-0.042026-08-03 → 2026-08-30
tmin12Znearestall28 1 QC1.14 [0.68, 1.63]1.15-0.19 [-0.83, 0.38]1.45 [0.91, 1.87]50% [29%, 80%]79%96%-0.03-0.042026-08-03 → 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 KSFO, lead day 2, 00Z bilinear tmax+10+50-5-102026-08-03: -6.66 °F2026-08-04: -5.4 °F2026-08-05: -5.56 °F2026-08-06: -5.22 °F2026-08-07: -0.76 °F2026-08-08: +0.51 °F2026-08-09: -0.05 °F2026-08-10: -6.27 °F2026-08-11: -9.02 °F2026-08-12: -8.96 °F2026-08-13: -8.92 °F2026-08-14: -6.24 °F2026-08-15: -4.53 °F2026-08-16: -3.27 °F2026-08-17: -6.49 °F2026-08-18: -1.52 °F2026-08-19: +1.13 °F2026-08-20: -4.18 °F2026-08-21: -2.78 °F2026-08-22: -2.35 °F2026-08-23: -8.09 °F2026-08-24: -6.95 °F2026-08-25: +0.91 °F2026-08-26: -5.94 °F2026-08-27: -3.11 °F2026-08-28: +1.58 °F2026-08-29: -6.16 °F2026-08-30: -5.72 °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
2026-08-30-5.72
2026-08-29-6.16
2026-08-28+1.58
2026-08-27-3.11
2026-08-26-5.94
2026-08-25+0.91
2026-08-24-6.95
2026-08-23-8.09
2026-08-22-2.35
2026-08-21-2.78
2026-08-20-4.18
2026-08-19+1.13
2026-08-18-1.52
2026-08-17-6.49
2026-08-16-3.27
2026-08-15-4.53
2026-08-14-6.24
2026-08-13-8.92
2026-08-12-8.96
2026-08-11-9.02
2026-08-10-6.27
2026-08-09-0.05
2026-08-08+0.51
2026-08-07-0.76
2026-08-06-5.22
2026-08-05-5.56
2026-08-04-5.40
2026-08-03-6.66

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSFO, lead day 2-10 to -9 °F: 1 day-9 to -8 °F: 3 days-8 to -7 °F: 0 days-7 to -6 °F: 6 days-6 to -5 °F: 5 days-5 to -4 °F: 2 days-4 to -3 °F: 2 days-3 to -2 °F: 2 days-2 to -1 °F: 1 day-1 to 0 °F: 2 days0 to 1 °F: 2 days1 to 2 °F: 2 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| 5.31 · P90 |e| 8.34 °F-100+10 °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
-10.00-9.001
-9.00-8.003
-8.00-7.000
-7.00-6.006
-6.00-5.005
-5.00-4.002
-4.00-3.002
-3.00-2.002
-2.00-1.001
-1.00+0.002
+0.00+1.002
+1.00+2.002
+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
2026-08284.58 -4.29

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 -2.62 [-2.62, -2.62] yes
FourCastNet v2 (IFS init) 1 +4.11 [4.11, 4.11] yes
NCEP GFS 28 +0.00 [-0.37, 0.33] no
GraphCast (IFS init) 26 -0.52 [-0.78, -0.19] yes
ECMWF IFS HRES 23 -1.53 [-2.40, -0.87] yes
Pangu-Weather (IFS init) 1 -0.67 [-0.67, -0.67] yes
Persistence (baseline) 28 +0.58 [-1.32, 2.21] no

Cite this page

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

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSFO (San Francisco Intl), 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/KSFO/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