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 · NCEP GFS · lead day 5

KSFO · gfs · lead 5

Target day = initialization date + 5 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, gfs-0p25, 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
tmax00Zbilinear30d25 1 QC4.69 [3.83, 5.70]2.67-4.30 [-5.19, -3.32]5.40 [4.38, 6.48]4% [0%, 14%]16%40%-0.11+0.352026-08-06 → 2026-08-30
tmax00Zbilinear90d25 1 QC4.69 [3.75, 5.95]2.67-4.30 [-5.39, -3.12]5.40 [4.23, 6.65]4% [0%, 17%]16%40%-0.11+0.352026-08-06 → 2026-08-30
tmax00Zbilinear365d25 1 QC4.69 [3.72, 6.26]2.67-4.30 [-5.49, -3.19]5.40 [4.16, 6.93]4% [0%, 16%]16%40%-0.11+0.352026-08-06 → 2026-08-30
tmax00Zbilinearall25 1 QC4.69 [3.78, 5.97]2.67-4.30 [-5.39, -3.28]5.40 [4.26, 6.73]4% [0%, 17%]16%40%-0.11+0.352026-08-06 → 2026-08-30
tmax00Znearest30d25 1 QC2.97 [1.73, 4.27]2.81+1.03 [-0.21, 2.44]3.96 [2.44, 5.37]24% [4%, 44%]48%60%+0.30+0.312026-08-06 → 2026-08-30
tmax00Znearest90d25 1 QC2.97 [1.75, 4.65]2.81+1.03 [-0.51, 2.82]3.96 [2.39, 5.86]24% [0%, 47%]48%60%+0.30+0.312026-08-06 → 2026-08-30
tmax00Znearest365d25 1 QC2.97 [1.58, 4.64]2.81+1.03 [-0.63, 2.72]3.96 [2.10, 5.70]24% [0%, 50%]48%60%+0.30+0.312026-08-06 → 2026-08-30
tmax00Znearestall25 1 QC2.97 [1.63, 4.74]2.81+1.03 [-0.49, 2.69]3.96 [2.15, 5.91]24% [0%, 47%]48%60%+0.30+0.312026-08-06 → 2026-08-30
tmax12Zbilinear30d25 1 QC4.49 [3.46, 5.42]2.63-4.18 [-5.07, -3.08]5.25 [4.25, 6.13]12% [3%, 24%]20%40%-0.06+0.362026-08-06 → 2026-08-30
tmax12Zbilinear90d25 1 QC4.49 [3.27, 5.62]2.63-4.18 [-5.19, -2.83]5.25 [4.05, 6.26]12% [0%, 25%]20%40%-0.06+0.362026-08-06 → 2026-08-30
tmax12Zbilinear365d25 1 QC4.49 [3.22, 5.86]2.63-4.18 [-5.25, -2.74]5.25 [4.03, 6.48]12% [0%, 25%]20%40%-0.06+0.362026-08-06 → 2026-08-30
tmax12Zbilinearall25 1 QC4.49 [3.33, 5.68]2.63-4.18 [-5.17, -2.91]5.25 [4.19, 6.31]12% [0%, 27%]20%40%-0.06+0.362026-08-06 → 2026-08-30
tmax12Znearest30d25 1 QC3.17 [1.90, 4.65]3.23+1.13 [-0.35, 3.00]4.15 [2.82, 5.43]32% [9%, 57%]40%52%+0.25+0.212026-08-06 → 2026-08-30
tmax12Znearest90d25 1 QC3.17 [1.82, 5.15]3.23+1.13 [-0.56, 3.53]4.15 [2.74, 5.82]32% [7%, 57%]40%52%+0.25+0.212026-08-06 → 2026-08-30
tmax12Znearest365d25 1 QC3.17 [1.72, 5.12]3.23+1.13 [-0.74, 3.55]4.15 [2.64, 5.76]32% [0%, 60%]40%52%+0.25+0.212026-08-06 → 2026-08-30
tmax12Znearestall25 1 QC3.17 [1.81, 5.16]3.23+1.13 [-0.71, 3.44]4.15 [2.74, 5.75]32% [0%, 60%]40%52%+0.25+0.212026-08-06 → 2026-08-30
tmin00Zbilinear30d25 1 QC0.98 [0.68, 1.19]0.74-0.63 [-0.99, -0.24]1.13 [0.84, 1.32]52% [37%, 74%]100%100%+0.12+0.352026-08-06 → 2026-08-30
tmin00Zbilinear90d25 1 QC0.98 [0.60, 1.20]0.74-0.63 [-1.01, -0.17]1.13 [0.75, 1.33]52% [36%, 80%]100%100%+0.12+0.352026-08-06 → 2026-08-30
tmin00Zbilinear365d25 1 QC0.98 [0.63, 1.22]0.74-0.63 [-1.02, -0.15]1.13 [0.76, 1.33]52% [36%, 80%]100%100%+0.12+0.352026-08-06 → 2026-08-30
tmin00Zbilinearall25 1 QC0.98 [0.54, 1.22]0.74-0.63 [-1.03, -0.12]1.13 [0.69, 1.33]52% [35%, 84%]100%100%+0.12+0.352026-08-06 → 2026-08-30
tmin00Znearest30d25 1 QC2.13 [1.64, 2.63]0.85-2.09 [-2.62, -1.51]2.37 [1.81, 2.86]16% [8%, 24%]40%80%-0.90+0.262026-08-06 → 2026-08-30
tmin00Znearest90d25 1 QC2.13 [1.60, 2.66]0.85-2.09 [-2.65, -1.41]2.37 [1.74, 2.88]16% [8%, 25%]40%80%-0.90+0.262026-08-06 → 2026-08-30
tmin00Znearest365d25 1 QC2.13 [1.62, 2.68]0.85-2.09 [-2.68, -1.48]2.37 [1.76, 2.92]16% [8%, 24%]40%80%-0.90+0.262026-08-06 → 2026-08-30
tmin00Znearestall25 1 QC2.13 [1.59, 2.68]0.85-2.09 [-2.66, -1.40]2.37 [1.72, 2.92]16% [8%, 26%]40%80%-0.90+0.262026-08-06 → 2026-08-30
tmin12Zbilinear30d25 1 QC0.97 [0.75, 1.15]0.90-0.47 [-0.90, 0.03]1.18 [0.98, 1.33]56% [39%, 75%]92%100%+0.13+0.222026-08-06 → 2026-08-30
tmin12Zbilinear90d25 1 QC0.97 [0.73, 1.16]0.90-0.47 [-0.89, 0.14]1.18 [0.95, 1.32]56% [39%, 79%]92%100%+0.13+0.222026-08-06 → 2026-08-30
tmin12Zbilinear365d25 1 QC0.97 [0.71, 1.17]0.90-0.47 [-0.92, 0.20]1.18 [0.95, 1.33]56% [38%, 78%]92%100%+0.13+0.222026-08-06 → 2026-08-30
tmin12Zbilinearall25 1 QC0.97 [0.70, 1.17]0.90-0.47 [-0.94, 0.23]1.18 [0.94, 1.34]56% [38%, 80%]92%100%+0.13+0.222026-08-06 → 2026-08-30
tmin12Znearest30d25 1 QC1.95 [1.40, 2.55]1.10-1.79 [-2.52, -1.09]2.27 [1.61, 2.81]24% [10%, 40%]56%76%-0.74+0.042026-08-06 → 2026-08-30
tmin12Znearest90d25 1 QC1.95 [1.31, 2.56]1.10-1.79 [-2.55, -0.98]2.27 [1.50, 2.82]24% [10%, 40%]56%76%-0.74+0.042026-08-06 → 2026-08-30
tmin12Znearest365d25 1 QC1.95 [1.35, 2.62]1.10-1.79 [-2.61, -1.01]2.27 [1.51, 2.88]24% [8%, 43%]56%76%-0.74+0.042026-08-06 → 2026-08-30
tmin12Znearestall25 1 QC1.95 [1.32, 2.61]1.10-1.79 [-2.57, -0.97]2.27 [1.49, 2.85]24% [9%, 43%]56%76%-0.74+0.042026-08-06 → 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 NCEP GFS at KSFO, lead day 5, 00Z bilinear tmax+20+100-10-202026-08-06: -4.89 °F2026-08-07: +0.99 °F2026-08-08: +1.43 °F2026-08-09: -5.45 °F2026-08-10: -6.46 °F2026-08-11: -7.1 °F2026-08-12: -4.03 °F2026-08-13: -3.33 °F2026-08-14: -2.95 °F2026-08-15: -2.84 °F2026-08-16: -5.67 °F2026-08-17: -6.14 °F2026-08-18: -4.88 °F2026-08-19: -1.81 °F2026-08-20: -2.16 °F2026-08-21: -2.77 °F2026-08-22: -1.2 °F2026-08-23: -9.77 °F2026-08-24: -7.63 °F2026-08-25: -2.67 °F2026-08-26: -10.03 °F2026-08-27: -3.66 °F2026-08-28: +2.53 °F2026-08-29: -7.89 °F2026-08-30: -9.05 °F2026-08-062026-08-30°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 (25 days, newest first) · download CSV
Climatological dayError °F
2026-08-30-9.05
2026-08-29-7.89
2026-08-28+2.53
2026-08-27-3.66
2026-08-26-10.03
2026-08-25-2.67
2026-08-24-7.63
2026-08-23-9.77
2026-08-22-1.20
2026-08-21-2.77
2026-08-20-2.16
2026-08-19-1.81
2026-08-18-4.88
2026-08-17-6.14
2026-08-16-5.67
2026-08-15-2.84
2026-08-14-2.95
2026-08-13-3.33
2026-08-12-4.03
2026-08-11-7.10
2026-08-10-6.46
2026-08-09-5.45
2026-08-08+1.43
2026-08-07+0.99
2026-08-06-4.89

Error distribution

Distribution of the signed daily error in °F for NCEP GFS at KSFO, lead day 5-20 to -18 °F: 0 days-18 to -16 °F: 0 days-16 to -14 °F: 0 days-14 to -12 °F: 0 days-12 to -10 °F: 1 day-10 to -8 °F: 2 days-8 to -6 °F: 5 days-6 to -4 °F: 5 days-4 to -2 °F: 7 days-2 to 0 °F: 2 days0 to 2 °F: 2 days2 to 4 °F: 1 day4 to 6 °F: 0 days6 to 8 °F: 0 days8 to 10 °F: 0 days10 to 12 °F: 0 days12 to 14 °F: 0 days14 to 16 °F: 0 days16 to 18 °F: 0 days18 to 20 °F: 0 daysdashed: P50 |e| 4.03 · P90 |e| 8.59 °F-200+20 °Fn = 25 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
-20.00-18.000
-18.00-16.000
-16.00-14.000
-14.00-12.000
-12.00-10.001
-10.00-8.002
-8.00-6.005
-6.00-4.005
-4.00-2.007
-2.00+0.002
+0.00+2.002
+2.00+4.001
+4.00+6.000
+6.00+8.000
+8.00+10.000
+10.00+12.000
+12.00+14.000
+14.00+16.000
+16.00+18.000
+18.00+20.000

Month by month

00Z bilinear daily maximum, newest first.

Monthn MAE °FBias °F
2026-08254.69 -4.30

Availability

ModelScored period DaysCoverage
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25
NCEP GFS2026-08-06 → 2026-08-30 25

Compared with other models

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

Other modelCommon days MAE difference °FDistinguishable
ECMWF AIFS Single 25 +0.18 [-0.81, 1.43] no
GraphCast (IFS init) 25 -0.86 [-1.60, 0.13] no
ECMWF IFS HRES 18 -1.30 [-2.16, -0.17] yes
Persistence (baseline) 25 +0.45 [-1.61, 1.71] no

Cite this page

ShortCastCheck, KSFO gfs lead 5, methodology v0.2, accessed 2026-08-31, https://castcheck.zifanzhang.com/station/KSFO/model/gfs/lead/5/

LongCastCheck (2026). Station-level verification of raw weather-model 2 m temperature forecasts: KSFO (San Francisco Intl), model gfs, lead day 5. Methodology version 0.2, schema version 0.1, data through 2026-08-30. Accessed 2026-08-31. https://castcheck.zifanzhang.com/station/KSFO/model/gfs/lead/5/

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