WattTime Forecasts API

openapi: 3.2.0
info:
  title: WattTime Forecasts API
  description: The WattTime Data API v3 provides access to real-time, forecast, and historical marginal emissions data for electric grids worldwide. Key signals include CO2 MOER (Marginal Operating Emissions Rate), health damage estimates, and CO2 AOER (Average Operating Emissions Rate). Coverage spans 342 grid regions in 210 countries and territories, with real-time data updated every five minutes. Authentication uses JWT bearer tokens obtained via the login endpoint using HTTP Basic Auth.
  version: '3.0'
  contact:
    name: WattTime Support
    email: support@watttime.org
    url: https://watttime.org/
  license:
    name: Proprietary
    url: https://watttime.org/data-plans/
  x-generated-from: documentation
servers:
- url: https://api.watttime.org/v3
  description: WattTime API v3 Production
- url: https://api2.watttime.org/v2
  description: WattTime API v2 Legacy
tags:
- name: Forecasts
  description: Retrieve emissions forecasts and historical forecast data.
paths:
  /forecast:
    get:
      operationId: getForecast
      summary: WattTime Get Emissions Forecast
      description: Retrieve the current emissions forecast for a specified grid region and signal type. Real-time data is available within 5 minutes via this endpoint, covering a 24-72 hour forecast horizon. This is the primary endpoint for carbon-aware scheduling applications.
      tags:
      - Forecasts
      security:
      - bearerAuth: []
      parameters:
      - name: region
        in: query
        required: true
        description: Grid region identifier (e.g., CAISO_NORTH).
        schema:
          type: string
        example: CAISO_NORTH
      - name: signal_type
        in: query
        required: true
        description: The emissions signal type to forecast.
        schema:
          type: string
          enum:
          - co2_moer
          - co2_aoer
          - health_damage
        example: co2_moer
      - name: horizon_hours
        in: query
        required: false
        description: Number of hours ahead to forecast. Maximum varies by region. Default returns the full available forecast window.
        schema:
          type: integer
          minimum: 1
          maximum: 72
        example: 24
      - name: model
        in: query
        required: false
        description: Model version date to use. Defaults to the latest model.
        schema:
          type: string
        example: '2026-03-01'
      responses:
        '200':
          description: Forecast emissions data for the requested region and signal.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ForecastResponse'
              examples:
                GetForecast200Example:
                  summary: Default getForecast 200 response
                  x-microcks-default: true
                  value:
                    meta:
                      region: CAISO_NORTH
                      signal_type: co2_moer
                      model:
                        date: '2026-03-01'
                      units: lbs_co2_per_mwh
                      generated_at: '2026-05-03T10:00:00+00:00'
                    data:
                    - point_time: '2026-05-03T10:05:00+00:00'
                      value: 387.2
                      version: '2026-03-01'
                    - point_time: '2026-05-03T10:10:00+00:00'
                      value: 391.4
                      version: '2026-03-01'
        '400':
          description: Bad request - invalid parameters.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '403':
          description: Forbidden - subscription plan does not include this region.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /forecast/historical:
    get:
      operationId: getForecastHistorical
      summary: WattTime Get Historical Forecast Data
      description: Retrieve previously generated forecast data for a specific historical time window. Useful for back-testing carbon-aware scheduling algorithms and analyzing forecast accuracy over time.
      tags:
      - Forecasts
      security:
      - bearerAuth: []
      parameters:
      - name: region
        in: query
        required: true
        description: Grid region identifier (e.g., CAISO_NORTH).
        schema:
          type: string
        example: CAISO_NORTH
      - name: signal_type
        in: query
        required: true
        description: The emissions signal type.
        schema:
          type: string
          enum:
          - co2_moer
          - co2_aoer
          - health_damage
        example: co2_moer
      - name: start
        in: query
        required: true
        description: Start of the historical forecast window (ISO 8601 UTC).
        schema:
          type: string
          format: date-time
        example: '2026-04-01T00:00:00Z'
      - name: end
        in: query
        required: true
        description: End of the historical forecast window (ISO 8601 UTC).
        schema:
          type: string
          format: date-time
        example: '2026-04-02T00:00:00Z'
      - name: model
        in: query
        required: false
        description: Model version date.
        schema:
          type: string
        example: '2026-03-01'
      responses:
        '200':
          description: Historical forecast data for the specified window.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ForecastResponse'
              examples:
                GetForecastHistorical200Example:
                  summary: Default getForecastHistorical 200 response
                  x-microcks-default: true
                  value:
                    meta:
                      region: CAISO_NORTH
                      signal_type: co2_moer
                      model:
                        date: '2026-03-01'
                      units: lbs_co2_per_mwh
                      generated_at: '2026-04-01T00:00:00+00:00'
                    data:
                    - point_time: '2026-04-01T00:05:00+00:00'
                      value: 405.1
                      version: '2026-03-01'
        '400':
          description: Bad request.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
components:
  schemas:
    ErrorResponse:
      type: object
      properties:
        error:
          type: string
          description: Error type or code.
          example: unauthorized
        message:
          type: string
          description: Human-readable error message.
          example: Invalid or expired token. Please re-authenticate.
        detail:
          type: string
          description: Additional error detail.
          example: Token has expired. Please call /login to get a new token.
    ForecastResponse:
      type: object
      properties:
        meta:
          $ref: '#/components/schemas/ForecastMeta'
        data:
          type: array
          description: Array of forecast data points.
          items:
            $ref: '#/components/schemas/DataPoint'
    ForecastMeta:
      type: object
      properties:
        region:
          type: string
          description: Grid region identifier.
          example: CAISO_NORTH
        signal_type:
          type: string
          description: Signal type of the forecast.
          example: co2_moer
        model:
          type: object
          properties:
            date:
              type: string
              description: Model version date.
              example: '2026-03-01'
        units:
          type: string
          description: Units for the forecast values.
          example: lbs_co2_per_mwh
        generated_at:
          type: string
          format: date-time
          description: Timestamp when the forecast was generated.
          example: '2026-05-03T10:00:00+00:00'
    DataPoint:
      type: object
      properties:
        point_time:
          type: string
          format: date-time
          description: Timestamp for the emissions data point (ISO 8601 UTC).
          example: '2026-04-01T00:00:00+00:00'
        value:
          type: number
          format: double
          description: Emissions value in the units specified by the response meta.
          example: 412.5
        version:
          type: string
          description: Model version used for this data point.
          example: '2026-03-01'
  securitySchemes:
    basicAuth:
      type: http
      scheme: basic
      description: HTTP Basic Authentication used only for the /login endpoint. Provide username and password to obtain a bearer token.
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: 'JWT bearer token obtained from the /login endpoint. Token expires after 30 minutes. Include as Authorization: Bearer {token} header.'