---
title: "Get a range of historical forecasted data"
method: GET
path: "/v3/forecast/historical"
tags: ["GET Forecast"]
---

# Get a range of historical forecasted data

`GET /v3/forecast/historical`

Returns forecast data for the specified `region`, `signal_type`, and time period. The response contains a `data`
list made up of `generated_at` and `forecast` pairs that cover the requested time period. The `forecast` list here
includes all the values that were generated at the `generated_at` time.`start` and `end` are used to specify which
`generated_at` forecasts will be returned. Individual queries are limited to 24 hours of `generated_at` forecasts
(the range of `start` to `end`; this limit equals 288 `generated_at` times).

## Query parameters

- `start` string, date-time, required — (inclusive) ISO8601-compliant timezone-aware date string indicating earliest desired forecast, _used to select the first `generated_at` time_
- `end` string, date-time, required — (inclusive) ISO8601-compliant timezone-aware date string indicating latest desired forecast, _used to select the last `generated_at` time_
- `region` string, required — Region abbreviation associated with location, from result of query to `/v3/region-from-loc`
- `signal_type` union, required — Use to select any available `signal_type` which is authorized for your account
  - 'co2_moer' | 'health_damage'
  - unknown
- `model` string, date, nullable — Use to return different models from defaults.
- `horizon_hours` integer — Length of forecast horizon in hours. Setting this parameter to `0` will return a single value of the most recently produced forecast

## Response `200`

Successful Response

- V3ExtendedForecastResponse
  - `data` APIV3ExtendedForecastType[], required
    - `generated_at` string, date-time, required
    - `forecast` APIV3DataResponseFormat[], required
      - `point_time` string, date-time, required
      - `value` number, required
      - `last_updated` string, date-time, nullable
      - `imputed_data_used` boolean, nullable
  - `meta` V3ForecastMetadata, required
    - `data_point_period_seconds` integer, required
    - `region` string, required
    - `signal_type` union, required
      - unknown
      - 'co2_moer' | 'health_damage'
    - `units` string, required
    - `warnings` WarningType[], required
      - `type` string, required
      - `message` string, required
    - `model` V3ModelMetadata
      - `date` string, date, required
      - `type` 'interchange' | 'average' | 'binned_regression' | 'heatrate' | 'proxy' | 'synthetic_proxy' | 'forecast'
    - `generated_at_period_seconds` integer, required

## Other responses

- `400` — Bad Request
- `403` — Forbidden
- `422` — Unprocessable Entity

---

[API](https://skmtc.dev/watttime/apis/watttime-data-api.md) · [All operations](https://skmtc.dev/watttime/apis/watttime-data-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/watttime/watttime-data-api/revisions/2c85341b2839/schema)