docsadvancedbias-correction

Bias Correction

GET/api/v1/accuracy/bias-correction

Applies a station's historical bias to a raw NWS forecast and returns the corrected value plus an expected range (p10–p90) and confidence interval. Pass the forecast you see and the date it applies to; the bias estimate uses the last `days` of verified pairs. Station is required.

Parameters

Name	Type	Required	Description
`station_id`	string	required	ICAO station identifier (or use city)
`city`	string	optional	City name or alias (resolves to station)
`forecast_temp`	float	optional	Raw NWS forecast (°F) to correct Default: 75
`forecast_for_date`	YYYY-MM-DD	optional	Date the forecast applies to Default: today
`days`	integer	optional	Historical window for the bias estimate Default: 90
`metric`	string	optional	high (default) or low — correct a daily-high or daily-low forecast Default: high

Response Fields

Field	Type	Description
`original_forecast`	float	The forecast_temp you passed
`corrected_forecast`	float	original_forecast + bias_adjustment
`bias_adjustment`	float	Correction applied (°F); negative when NWS runs warm at this station
`expected_range`	object	{ p10, p25, p50, p75, p90 } of likely observed values
`confidence_interval`	object	{ lower_bound, upper_bound }
`forecast_range`	string	Human-readable range label (e.g. 78-82°F)
`sample_size`	integer	Verification pairs behind the estimate
`forecast_for_date`	string	Target date used
`data_period_start / data_period_end`	string	Historical window actually used

← Peak Timing

Exceedance →

cURL

curl -s -H "Authorization: Bearer $API_KEY" "https://api.deltadaemon.com/api/v1/accuracy/bias-correction?station_id=KLAX&forecast_temp=78&forecast_for_date=2026-02-21&days=30"

JSON

{
  "success": true,
  "data": {
    "original_forecast": 78,
    "corrected_forecast": 79.13,
    "bias_adjustment": 1.13,
    "expected_range": { "p10": 74.5, "p25": 76.8, "p50": 79.1, "p75": 81.4, "p90": 83.8 },
    "confidence_interval": { "lower_bound": 71.42, "upper_bound": 86.83 },
    "forecast_range": "78-82°F",
    "station_id": "KLAX",
    "city_name": "Los Angeles",
    "timezone": "America/Los_Angeles",
    "sample_size": 20,
    "forecast_for_date": "2026-02-21",
    "as_of_timestamp": "2026-02-20T23:55:00Z",
    "data_period_start": "2026-01-21",
    "data_period_end": "2026-02-20",
    "historical_accuracy_note": "Based on 20 verification pairs."
  },
  "metadata": {
    "generated_at": "2026-02-20T23:55:00Z",
    "local_generated_at": "2026-02-20T15:55:00-08:00",
    "days_analyzed": 30,
    "total_records": 20,
    "station_id": "KLAX",
    "station_timezone": "America/Los_Angeles",
    "forecast_for_date": "2026-02-21",
    "accuracy_metric": "high"
  }
}

cURL

curl -s -H "Authorization: Bearer $API_KEY" "https://api.deltadaemon.com/api/v1/accuracy/bias-correction?station_id=KLAX&forecast_temp=78&forecast_for_date=2026-02-21&days=30"

JSON

{
  "success": true,
  "data": {
    "original_forecast": 78,
    "corrected_forecast": 79.13,
    "bias_adjustment": 1.13,
    "expected_range": { "p10": 74.5, "p25": 76.8, "p50": 79.1, "p75": 81.4, "p90": 83.8 },
    "confidence_interval": { "lower_bound": 71.42, "upper_bound": 86.83 },
    "forecast_range": "78-82°F",
    "station_id": "KLAX",
    "city_name": "Los Angeles",
    "timezone": "America/Los_Angeles",
    "sample_size": 20,
    "forecast_for_date": "2026-02-21",
    "as_of_timestamp": "2026-02-20T23:55:00Z",
    "data_period_start": "2026-01-21",
    "data_period_end": "2026-02-20",
    "historical_accuracy_note": "Based on 20 verification pairs."
  },
  "metadata": {
    "generated_at": "2026-02-20T23:55:00Z",
    "local_generated_at": "2026-02-20T15:55:00-08:00",
    "days_analyzed": 30,
    "total_records": 20,
    "station_id": "KLAX",
    "station_timezone": "America/Los_Angeles",
    "forecast_for_date": "2026-02-21",
    "accuracy_metric": "high"
  }
}