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 3

KSFO · aifs_single · lead 3

Target day = initialization date + 3 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
tmax00Zbilinear30d27 1 QC4.42 [3.57, 5.48]2.55-4.17 [-5.30, -3.29]5.20 [4.31, 6.10]15% [4%, 24%]22%33%-0.28+0.202026-08-04 → 2026-08-30
tmax00Zbilinear90d27 1 QC4.42 [3.50, 5.54]2.55-4.17 [-5.39, -3.21]5.20 [4.21, 6.14]15% [3%, 25%]22%33%-0.28+0.202026-08-04 → 2026-08-30
tmax00Zbilinear365d27 1 QC4.42 [3.43, 5.69]2.55-4.17 [-5.52, -3.15]5.20 [4.15, 6.23]15% [0%, 25%]22%33%-0.28+0.202026-08-04 → 2026-08-30
tmax00Zbilinearall27 1 QC4.42 [3.55, 5.58]2.55-4.17 [-5.47, -3.22]5.20 [4.24, 6.17]15% [0%, 25%]22%33%-0.28+0.202026-08-04 → 2026-08-30
tmax00Znearest30d27 1 QC2.90 [2.25, 3.51]2.80-0.50 [-1.84, 0.81]3.50 [2.90, 4.00]30% [17%, 44%]41%48%+0.16+0.132026-08-04 → 2026-08-30
tmax00Znearest90d27 1 QC2.90 [2.16, 3.59]2.80-0.50 [-1.98, 1.09]3.50 [2.84, 4.03]30% [14%, 47%]41%48%+0.16+0.132026-08-04 → 2026-08-30
tmax00Znearest365d27 1 QC2.90 [2.10, 3.64]2.80-0.50 [-2.21, 1.10]3.50 [2.77, 4.07]30% [12%, 50%]41%48%+0.16+0.132026-08-04 → 2026-08-30
tmax00Znearestall27 1 QC2.90 [2.13, 3.61]2.80-0.50 [-2.14, 1.07]3.50 [2.82, 4.08]30% [13%, 50%]41%48%+0.16+0.132026-08-04 → 2026-08-30
tmax12Zbilinear30d27 1 QC4.74 [3.83, 5.83]2.72-4.51 [-5.72, -3.60]5.53 [4.60, 6.48]11% [4%, 18%]22%33%-0.38+0.152026-08-04 → 2026-08-30
tmax12Zbilinear90d27 1 QC4.74 [3.76, 5.94]2.72-4.51 [-5.78, -3.52]5.53 [4.47, 6.52]11% [0%, 18%]22%33%-0.38+0.152026-08-04 → 2026-08-30
tmax12Zbilinear365d27 1 QC4.74 [3.72, 6.03]2.72-4.51 [-5.91, -3.51]5.53 [4.42, 6.62]11% [0%, 18%]22%33%-0.38+0.152026-08-04 → 2026-08-30
tmax12Zbilinearall27 1 QC4.74 [3.84, 5.99]2.72-4.51 [-5.92, -3.56]5.53 [4.55, 6.56]11% [0%, 19%]22%33%-0.38+0.152026-08-04 → 2026-08-30
tmax12Znearest30d27 1 QC3.01 [2.17, 3.78]2.89-0.86 [-2.29, 0.40]3.63 [2.86, 4.23]30% [13%, 50%]33%44%+0.13+0.102026-08-04 → 2026-08-30
tmax12Znearest90d27 1 QC3.01 [2.00, 3.86]2.89-0.86 [-2.39, 0.59]3.63 [2.64, 4.28]30% [11%, 54%]33%44%+0.13+0.102026-08-04 → 2026-08-30
tmax12Znearest365d27 1 QC3.01 [1.91, 3.97]2.89-0.86 [-2.58, 0.61]3.63 [2.59, 4.34]30% [8%, 56%]33%44%+0.13+0.102026-08-04 → 2026-08-30
tmax12Znearestall27 1 QC3.01 [2.06, 3.93]2.89-0.86 [-2.54, 0.56]3.63 [2.74, 4.32]30% [8%, 55%]33%44%+0.13+0.102026-08-04 → 2026-08-30
tmin00Zbilinear30d27 1 QC1.18 [0.99, 1.39]0.96-0.62 [-1.10, -0.05]1.39 [1.17, 1.62]52% [38%, 63%]85%96%-0.23+0.002026-08-04 → 2026-08-30
tmin00Zbilinear90d27 1 QC1.18 [0.96, 1.40]0.96-0.62 [-1.14, -0.02]1.39 [1.12, 1.62]52% [38%, 65%]85%96%-0.23+0.002026-08-04 → 2026-08-30
tmin00Zbilinear365d27 1 QC1.18 [0.96, 1.40]0.96-0.62 [-1.11, 0.05]1.39 [1.14, 1.62]52% [38%, 64%]85%96%-0.23+0.002026-08-04 → 2026-08-30
tmin00Zbilinearall27 1 QC1.18 [0.96, 1.41]0.96-0.62 [-1.20, 0.00]1.39 [1.14, 1.62]52% [36%, 65%]85%96%-0.23+0.002026-08-04 → 2026-08-30
tmin00Znearest30d27 1 QC1.20 [0.79, 1.57]1.15-0.28 [-0.87, 0.34]1.48 [1.08, 1.82]44% [27%, 68%]81%96%-0.25-0.192026-08-04 → 2026-08-30
tmin00Znearest90d27 1 QC1.20 [0.64, 1.61]1.15-0.28 [-0.91, 0.38]1.48 [0.89, 1.84]44% [25%, 74%]81%96%-0.25-0.192026-08-04 → 2026-08-30
tmin00Znearest365d27 1 QC1.20 [0.70, 1.63]1.15-0.28 [-0.92, 0.39]1.48 [0.94, 1.88]44% [25%, 71%]81%96%-0.25-0.192026-08-04 → 2026-08-30
tmin00Znearestall27 1 QC1.20 [0.66, 1.62]1.15-0.28 [-0.97, 0.37]1.48 [0.94, 1.87]44% [24%, 75%]81%96%-0.25-0.192026-08-04 → 2026-08-30
tmin12Zbilinear30d27 1 QC1.26 [1.04, 1.47]0.95-0.75 [-1.22, -0.18]1.44 [1.23, 1.64]37% [19%, 50%]85%96%-0.30+0.022026-08-04 → 2026-08-30
tmin12Zbilinear90d27 1 QC1.26 [1.02, 1.48]0.95-0.75 [-1.27, -0.17]1.44 [1.20, 1.66]37% [17%, 52%]85%96%-0.30+0.022026-08-04 → 2026-08-30
tmin12Zbilinear365d27 1 QC1.26 [1.01, 1.48]0.95-0.75 [-1.26, -0.13]1.44 [1.20, 1.66]37% [17%, 52%]85%96%-0.30+0.022026-08-04 → 2026-08-30
tmin12Zbilinearall27 1 QC1.26 [0.99, 1.50]0.95-0.75 [-1.35, -0.17]1.44 [1.21, 1.67]37% [13%, 54%]85%96%-0.30+0.022026-08-04 → 2026-08-30
tmin12Znearest30d27 1 QC1.18 [0.73, 1.57]1.12-0.38 [-0.96, 0.20]1.49 [1.07, 1.84]44% [23%, 71%]81%96%-0.22-0.162026-08-04 → 2026-08-30
tmin12Znearest90d27 1 QC1.18 [0.56, 1.68]1.12-0.38 [-1.00, 0.25]1.49 [0.88, 1.88]44% [22%, 82%]81%96%-0.22-0.162026-08-04 → 2026-08-30
tmin12Znearest365d27 1 QC1.18 [0.57, 1.69]1.12-0.38 [-1.01, 0.25]1.49 [0.86, 1.91]44% [21%, 79%]81%96%-0.22-0.162026-08-04 → 2026-08-30
tmin12Znearestall27 1 QC1.18 [0.58, 1.66]1.12-0.38 [-1.05, 0.23]1.49 [0.91, 1.89]44% [21%, 82%]81%96%-0.22-0.162026-08-04 → 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 3, 00Z bilinear tmax+10+50-5-102026-08-04: -4.45 °F2026-08-05: -5.31 °F2026-08-06: -5.6 °F2026-08-07: -0.7 °F2026-08-08: +1.03 °F2026-08-09: -1.52 °F2026-08-10: -5.07 °F2026-08-11: -9.34 °F2026-08-12: -7.96 °F2026-08-13: -8.41 °F2026-08-14: -6.6 °F2026-08-15: -4.61 °F2026-08-16: -3.55 °F2026-08-17: -6.89 °F2026-08-18: -0 °F2026-08-19: +0.31 °F2026-08-20: -3.76 °F2026-08-21: -2.88 °F2026-08-22: -2.41 °F2026-08-23: -9.35 °F2026-08-24: -6.75 °F2026-08-25: -0.05 °F2026-08-26: -4.93 °F2026-08-27: -4.08 °F2026-08-28: +2.02 °F2026-08-29: -5.85 °F2026-08-30: -5.86 °F2026-08-042026-08-30°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 (27 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-5.86
2026-08-29-5.85
2026-08-28+2.02
2026-08-27-4.08
2026-08-26-4.93
2026-08-25-0.05
2026-08-24-6.75
2026-08-23-9.35
2026-08-22-2.41
2026-08-21-2.88
2026-08-20-3.76
2026-08-19+0.31
2026-08-18-0.00
2026-08-17-6.89
2026-08-16-3.55
2026-08-15-4.61
2026-08-14-6.60
2026-08-13-8.41
2026-08-12-7.96
2026-08-11-9.34
2026-08-10-5.07
2026-08-09-1.52
2026-08-08+1.03
2026-08-07-0.70
2026-08-06-5.60
2026-08-05-5.31
2026-08-04-4.45

Error distribution

Distribution of the signed daily error in °F for ECMWF AIFS Single at KSFO, lead day 3-10 to -9 °F: 2 days-9 to -8 °F: 1 day-8 to -7 °F: 1 day-7 to -6 °F: 3 days-6 to -5 °F: 5 days-5 to -4 °F: 4 days-4 to -3 °F: 2 days-3 to -2 °F: 2 days-2 to -1 °F: 1 day-1 to 0 °F: 3 days0 to 1 °F: 1 day1 to 2 °F: 1 day2 to 3 °F: 1 day3 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| 4.61 · P90 |e| 8.14 °F-100+10 °Fn = 27 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
-10.00-9.002
-9.00-8.001
-8.00-7.001
-7.00-6.003
-6.00-5.005
-5.00-4.004
-4.00-3.002
-3.00-2.002
-2.00-1.001
-1.00+0.003
+0.00+1.001
+1.00+2.001
+2.00+3.001
+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
2026-08274.42 -4.17

Availability

ModelScored period DaysCoverage
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27
ECMWF AIFS Single2026-08-04 → 2026-08-30 27

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 27 -0.28 [-0.85, 0.30] no
GraphCast (IFS init) 25 -0.76 [-0.94, -0.52] yes
ECMWF IFS HRES 22 -1.55 [-2.76, -0.03] yes
Persistence (baseline) 27 +0.97 [-0.53, 2.03] no

Cite this page

ShortCastCheck, KSFO aifs_single lead 3, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSFO/model/aifs_single/lead/3/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSFO (San Francisco Intl), model aifs_single, lead day 3. 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/3/

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