WeatherPerch report
Forecast revisions and confidence signals
This report describes how forecasts change and, only after enough matched forecast and observation records exist, how closely they have tracked observed weather. It is not a guarantee of future accuracy.
Current verification status
openmeteo · 0-day horizon · 1026 matched forecasts · high MAE 1.6° (95% interval ±0.1°)
openmeteo · 1-day horizon · 681 matched forecasts · high MAE 2.2° (95% interval ±0.2°)
openmeteo · 2-day horizon · 636 matched forecasts · high MAE 2.3° (95% interval ±0.2°)
openweather · 0-day horizon · 320 matched forecasts · high MAE 3.1° (95% interval ±0.5°)
nws · 0-day horizon · 221 matched forecasts · high MAE 2.3° (95% interval ±0.4°)
openmeteo · 3-day horizon · 530 matched forecasts · high MAE 2.6° (95% interval ±0.3°)
nws · 1-day horizon · 145 matched forecasts · high MAE 2.7° (95% interval ±0.5°)
openmeteo · 4-day horizon · 515 matched forecasts · high MAE 3° (95% interval ±0.4°)
openweather · 1-day horizon · 228 matched forecasts · high MAE 3.3° (95% interval ±0.6°)
nws · 2-day horizon · 130 matched forecasts · high MAE 2.7° (95% interval ±0.5°)
openmeteo · 5-day horizon · 514 matched forecasts · high MAE 3.7° (95% interval ±0.4°)
openweather · 2-day horizon · 228 matched forecasts · high MAE 3.2° (95% interval ±0.6°)
nws · 3-day horizon · 120 matched forecasts · high MAE 2.9° (95% interval ±0.7°)
openweather · 3-day horizon · 228 matched forecasts · high MAE 3.6° (95% interval ±0.6°)
nws · 4-day horizon · 120 matched forecasts · high MAE 3.1° (95% interval ±0.7°)
nws · 5-day horizon · 120 matched forecasts · high MAE 3.3° (95% interval ±0.7°)
nws · 6-day horizon · 62 matched forecasts · high MAE 3.3° (95% interval ±0.9°)
openweather · 4-day horizon · 136 matched forecasts · high MAE 3.5° (95% interval ±0.8°)
openmeteo · 6-day horizon · 209 matched forecasts · high MAE 3.8° (95% interval ±0.7°)
Precipitation-probability skill
openmeteo · 0-day horizon · 1026 matched forecasts · Brier score 0.17 (lower is better, 0 = perfect) · ROC-AUC 0.94
openmeteo · 1-day horizon · 681 matched forecasts · Brier score 0.17 (lower is better, 0 = perfect) · ROC-AUC 0.93
openmeteo · 2-day horizon · 636 matched forecasts · Brier score 0.17 (lower is better, 0 = perfect) · ROC-AUC 0.93
openweather · 0-day horizon · 320 matched forecasts · Brier score 0.22 (lower is better, 0 = perfect) · ROC-AUC 0.86
nws · 0-day horizon · 221 matched forecasts · Brier score 0.26 (lower is better, 0 = perfect) · ROC-AUC 0.93
openmeteo · 3-day horizon · 530 matched forecasts · Brier score 0.21 (lower is better, 0 = perfect) · ROC-AUC 0.88
nws · 1-day horizon · 145 matched forecasts · Brier score 0.23 (lower is better, 0 = perfect) · ROC-AUC 0.92
openmeteo · 4-day horizon · 515 matched forecasts · Brier score 0.23 (lower is better, 0 = perfect) · ROC-AUC 0.87
openweather · 1-day horizon · 228 matched forecasts · Brier score 0.21 (lower is better, 0 = perfect) · ROC-AUC 0.84
nws · 2-day horizon · 130 matched forecasts · Brier score 0.3 (lower is better, 0 = perfect) · ROC-AUC 0.9
openmeteo · 5-day horizon · 514 matched forecasts · Brier score 0.22 (lower is better, 0 = perfect) · ROC-AUC 0.84
openweather · 2-day horizon · 228 matched forecasts · Brier score 0.23 (lower is better, 0 = perfect) · ROC-AUC 0.81
nws · 3-day horizon · 120 matched forecasts · Brier score 0.36 (lower is better, 0 = perfect) · ROC-AUC 0.85
openweather · 3-day horizon · 228 matched forecasts · Brier score 0.22 (lower is better, 0 = perfect) · ROC-AUC 0.83
nws · 4-day horizon · 120 matched forecasts · Brier score 0.35 (lower is better, 0 = perfect) · ROC-AUC 0.73
nws · 5-day horizon · 120 matched forecasts · Brier score 0.34 (lower is better, 0 = perfect) · ROC-AUC 0.7
nws · 6-day horizon · 62 matched forecasts · Brier score 0.29 (lower is better, 0 = perfect) · ROC-AUC 0.68
openweather · 4-day horizon · 136 matched forecasts · Brier score 0.36 (lower is better, 0 = perfect) · ROC-AUC 0.74
openmeteo · 6-day horizon · 209 matched forecasts · Brier score 0.19 (lower is better, 0 = perfect) · ROC-AUC 0.89
Brier score measures how well the forecast probability matched the actual rain/no-rain outcome; ROC-AUC measures how well the forecast probability ranks days that got rain above days that did not.
Provider disagreement
353 recent location/date comparisons · average daily-high spread 2.7°
A spread is a signal of forecast uncertainty, not a ranking of providers or a guarantee that the widest value is wrong.
What is measured
Forecast vintages are retained with their issue time, target date, provider, horizon, and predicted values. Completed-day observations are matched to the same location and target date.
Qualified groups report mean absolute error (MAE), bias, root mean square error (RMSE), precipitation occurrence accuracy, sample size, and an approximate 95% confidence interval. Groups with fewer than 30 high-temperature matches remain clearly marked as insufficient.
Values are provider-specific and location-dependent. Archive observations may lag live conditions. A forecast revision is a change in a forecast, not proof that the earlier forecast was wrong. Official warnings take priority for safety decisions.