pyweatherflowudp

pyweatherflowudp

An event-based asynchronous library to read UDP packets from Weatherflow weather systems on a local network without any reliance on the cloud.

The atomic data provided by WeatherFlow sensors is all natively metric. To help facilitate transformations to other units or to perform calculations and comparisons, this module utilizes Pint's Quantity class as the type of most properties which have a unit of measurement. See the Quantity section below for more details.

This module utilizes PsychroLib to help with additional weather calculations that are derived from the various data points provided by the actual WeatherFlow sensors. While WeatherFlow has these additional data points available via the app and rest API, they are unavailable via the low-level UDP packet data. And while a list of derived metrics and the associated equations has been posted, they can be quite complex to implement, such as calculating wet bulb temperature. As such, PsychroLib is an invaluable resource since the work has already been done and it eliminates the need to write all the equations in this module (and potentially get them wrong). You may notice that some of these values aren't an exact match with what is shown in the WeatherFlow app because there are different formulas (some simpler, some more complex) to calculate derived weather metrics. This is because WeatherFlow and PsychroLib may have chosen one of the sometimes many different formulas to get the result desired. They should still be relatively close, however.

Supported Devices

• Tempest
• Air (untested)
• Sky (untested)

Usage

The primary way of interacting with this module, and the devices that are found with it, is via event subscriptions.

The classes and events which they currently support are outlined below, but you can also see an example tying this altogether in demo.py.

Client

WeatherFlowListener

• EVENT_DEVICE_DISCOVERED - emitted when a new device (Hub, Air, Sky or Tempest) is disovered for the first time

The classes and events in this section can be imported from pyweatherflowudp.client.

Devices

HubDevice

• EVENT_LOAD_COMPLETE - emitted once when the hub has finished parsing a status update for the first time
• EVENT_STATUS_UPDATE - emitted each time a status update has been parsed by the hub, including immediately following an EVENT_LOAD_COMPLETE

WeatherFlowSensorDevice (base class for AirDevice, SkyDevice and TempestDevice)

• EVENT_LOAD_COMPLETE - emitted once when the sensor has finished parsing one status update and one observation for the first time
• EVENT_OBSERVATION - emitted each time an observation has been parsed by the sensor
• EVENT_STATUS_UPDATE - emitted each time a status update has been parsed by the sensor

AirSensorType (AirDevice / TempestDevice)

• EVENT_STRIKE - emitted when a lightning strike has been detected

SkySensorType (SkyDevice / TempestDevice)

• EVENT_RAIN_START - emitted when rain has been detected
• EVENT_RAPID_WIND - emitted every 3 seconds (or less frequently depending on battery voltage) to inform about current wind condtions

The classes and events in this section can be imported from pyweatherflowudp.device.

Properties and Methods

WeatherFlowListener

property	type	description
devices	list	The known devices.
hubs	list	The known hubs.
is_listening	bool	True if the listener is currently monitoring UDP packets on the network, else False.
sensors	list	The known sensors.

WeatherFlowDevice

Base for hubs and sensors.

property	type	description
firmware_revision	str	The current firmware revision of the device.
load_complete	bool	True if the device has parsed all initial updates, else False.
model	str	The model of the device ("Hub", "Air", "Sky", "Tempest").
rssi	Quantity	The signal strength of the device in decibels.
serial_number	str	The serial number of the device.
timestamp	datetime	The UTC timestamp from the last status update.
up_since	datetime	The UTC timestamp the device started up and has since been running.
uptime	int	The number of seconds the device has been up and running.

HubDevice

property	type	description
reset_flags	list	The current reset flags of the hub.

WeatherFlowSensorDevice

Base for sensors.

property	type	description
battery	Quantity	The current battery voltage.
hub_rssi	Quantity	The signal strength of the hub in decibels.
hub_sn	str	The serial number of the hub the sensor belongs to.
last_report	datetime	The UTC timestamp from the last observation.
sensor_status	list	The list of issues the sensor is currently reporting.
report_interval	Quantity	The report interval in minutes.
reset_flags	list	The current reset flags of the hub.

AirSensorType

Base for "air" sensor measurements (Air/Tempest).

property	type	description
air_temperature	Quantity	The current air temperature in degrees Celsius.
last_lightning_strike_event	LightningStrikeEvent	The last lightning strike event.
lightning_strike_average_distance	Quantity	The average distance for lightning strikes in kilometers.
lightning_strike_count	int	The number of lightning strikes.
relative_humidity	Quantity	The relative humidity percentage.
station_pressure	Quantity	The observed station pressure in millibars.
air_density*	Quantity	The calculated air density in kilograms per cubic meter.
delta_t*	Quantity	The calculated Delta T in delta degrees Celsius.
dew_point_temperature*	Quantity	The calculated dew point temperature in degrees Celsius.
heat_index*	Quantity	The calculated heat index in degrees Celsius.
vapor_pressure*	Quantity	The calculated vapor pressure in millibars.
wet_bulb_temperature*	Quantity	The calculated wet bulb temperature in degrees Celsius.

* Indicates derived properties

method	input (type)	return	description
calculate_cloud_base	altitude (Quantity)	Quantity	Calculate the estimated altitude above mean sea level (AMSL) to the cloud base.
calculate_freezing_level	altitude (Quantity)	Quantity	Calculate the estimated altitude above mean sea level (AMSL) where the temperature is at the freezing point (0°C/32°F).
calculate_sea_level_pressure	altitude (Quantity)	Quantity	Calculate the sea level pressure in millibars (mbar).

SkySensorType

Base for "sky" sensor measurements (Sky/Tempest).

property	type	description
illuminance	Quantity	The current illuminance in Lux.
last_rain_start_event	RainStartEvent	The last rain start event.
last_wind_event	WindEvent	The last wind event.
precipitation_type	PrecipitationType	The current precipitation type: (NONE, RAIN, HAIL or RAIN_HAIL).
rain_accumulation_previous_minute	Quantity	The rain accumulation from the previous minute in millimeters.
rain_rate*	Quantity	The rain rate in millimeters per hour (based on the previous minute accumulation).
solar_radiation	Quantity	The solar radiation in Watts per cubic meter.
uv	int	The current UV index.
wind_average	Quantity	The wind speed average over the report interval in meters per second.
wind_direction	Quantity	The wind direction over the report interval in degrees.
wind_direction_cardinal	string	The wind direction cardinal (16-wind compass rose).
wind_gust	Quantity	The wind gust (maximum 3 second sample) in meters per second.
wind_lull	Quantity	The wind lull (minimum 3 second sample) in meters per second.
wind_sample_interval	Quantity	The wind sample interval in seconds.
wind_speed	Quantity	The wind speed in meters per second.

* Indicates derived properties

TempestDevice

property	type	description
feels_like_temperature*	Quantity	The calculated "feels like" temperature in degrees Celsius.
wind_chill_temperature*	Quantity	The calculated wind chill temperature in degrees Celsius.

* Indicates derived properties

Quantity

The pint.Quantity class has been utilized for device properties which are associated with a unit of measurement. This allows a conversion from the native metric unit to another of the user's choice such as degrees Celsius to degrees Fahrenheit, which produces another pint.Quantity:

device.air_temperature.to("degF")

To retrieve only the numeric value of a property, you can just append a .magnitude (or .m short form) like:

device.air_temperature.m

You can also retrieve only the units portion of a property with .units (or .u short form) like:

device.air_temperature.u

Check out the Pint docs for more tips.