Dark Sky Agent

Powered by Dark Sky

This agent provides the ability to query for current and forecast weather data from Dark Sky. The agent extends BaseWeatherAgent that provides caching of recently requested data, API call tracking, as well as mapping of weather point names from Darksky's naming scheme to the standardized CF-conventions scheme.


The Dark Sky agent requires the Pint package. This package can be installed in an activated environment with:

pip install pint

Dark Sky Endpoints

The Dark Sky agent provides the following endpoints in addition to those included with the base weather agent:

Get Minutely Forecast Data

RPC call to weather service method ‘get_minutely_forecast’


  • locations - List of dictionaries containing location details. Dark Sky requires

[{"lat": <lattitude>, "long": <longitude>},...]

optional parameters:

  • minutes - The number of minutes for which forecast data should

    be returned. By default, it is 60 minutes as well as the current minute. Dark Sky does not provide minutely data for more than one hour (60 minutes) into the future.

Get Daily Forecast Data

RPC call to weather service method ‘get_minutely_forecast’


  • locations - List of dictionaries containing location details. Dark Sky requires

[{"lat": <lattitude>, "long": <longitude>},...]

optional parameters:

  • days - The number of days for which forecast data should be returned. By default, it is the next 7 days as well as the current day.

Please note: If your forecast request to the Dark Sky agent asks for more data points than the default, the agent must use an additional API calls; an additional API call will be used to fetch any records not included in the default forecast request for the current day, and one additional call for each subsequent day of data the request would require, regardless of Dark Sky agent endpoint (If requesting 60 hours of hourly data Monday night at 8PM, 3 API calls must be made to fulfill the request: one for the initial request containing 48 hours of data, one for the remaining 4 hours of Wednesday evening's data, and one for records in Thursday's forecast).


The following is an example configuration for the Dark Sky agent. The "api_key" parameter is required while all others are optional.


  1. "api_key" - api key string provided by Dark Sky - this is required and will not be provided by the VOLTTRON team.

  2. "api_calls_limit" - limit of api calls that can be made to the remote before the agent no longer returns weather results. The agent will keep track of number of api calls and return an error when the limit is reached without attempting a connection to dark sky server. This is primarily used to prevent possible charges. If set to -1, no limit will be applied by the agent. Dark sky api might return a error after limit is exceeded. Defaults to -1

  3. "database_file" - sqlite database file for weather data caching. Defaults to "weather.sqlite" in the agent's data directory.

  4. "max_size_gb" - maximum size of cache database. When cache exceeds this size, data will get purged from cache till cache is within the configured size.

  5. "poll_locations - list of locations to periodically poll for current data.

  6. "poll_interval" - polling frequency or the number of seconds between each poll.

  7. "performance_mode" - If set to true, request response will exclude extra data points (this is primarily useful for reducing network traffic). If set to false, all data points are included in the response, and extra data is cached (to reduce the number of API calls used for future RPC calls). Defaults to True.

Example configuration:

    "api_key": "<api key string>",
    "api_calls_limit": 1000,
    "database_file": "weather.sqlite",
    "max_size_gb": 1,
    "poll_locations": [{"lat": 39.7555, "long": -105.2211},
                       {"lat": 46.2804, "long": -119.2752}],
    "poll_interval": 60

Registry Configuration

The registry configuration file for this agent can be found in agent's data directory. This configuration provides the point name mapping from the Dark Sky API's point scheme to the CF-conventions scheme by default. Points that do not specify "Standard_Point_Name" were found to not have a logical match to any point found in the CF-Conventions. For these points Dark Sky point name convention (Service_Point_Name) will be used.







millimeter / hour

meter / second














The Dark Sky agent requires an API key to be configured in order for users to request data. A user of the Dark Sky agent must obtain the key themselves.

API call tracking features will work only when each agent instance uses its own api key. If API key is shared across multiple dark sky agent instances, disable this feature by setting api_calls_limit = -1.

As of writing, dark sky gives 1000 daily API calls free for a trial account. Once this limit is reached, the error "daily usage limit exceeded" is returned. See https://darksky.net/dev for details

By default performance mode is set to True and for a given location and time period only the requested data points are returned. Set performance_mode to False to query all available data for a given location and time period if you want to cache all the data points for future retrieval there by reducing number of API calls.