Icelandic Met Office Weather for Home Assistant

A Home Assistant custom integration that exposes current weather observation and forecast data from the Icelandic Met Office through vedur.is.

This project is not affiliated with or endorsed by the Icelandic Met Office. Weather data is provided by the Icelandic Met Office (vedur.is).

Features

• UI config flow with full station browsing, map-based nearby station suggestions, or place search that opens the map near the matched location.
• Optional weather for Home, using Home Assistant's home zone. Enabled by default.
• Optional station selection for additional station weather entities.
• Station selector labels include station distance in nearby mode and the station owner when provided by the API.
• Multiple optional stations in one config entry.
• Optional weather and diagnostic entities for selected stations. Enabled by default.
• Optional weather entities that follow Home Assistant person entities. Enabled by default.
• Optional weather entities that follow selected device_tracker entities, such as route or destination trackers. Configure the trackers from the integration options.
• Hourly forecasts through weather.get_forecasts, using Vedur.is XML forecast time points.
• Optional daily and twice-daily forecasts. These are disabled by default because Vedur.is does not expose native daily or twice-daily forecast products through the APIs used by this integration. When enabled, they are derived from future XML time points using period high/low temperatures, max wind, and the most common mapped condition in the relevant daytime or day/night period.
• Processed 10-minute observations, polled every 10 minutes through a DataUpdateCoordinator. After the immediate startup refresh, successful polls are aligned to 75 seconds after each UTC 10-minute boundary to allow the Met Office processing pipeline time to publish new observations.
• Transient API failures retry after approximately 2, 5, 10, 20, and 40 minutes before progressively backing off to a maximum of six hours.
• Diagnostic sensors for condition, temperature, humidity, dew point, wind speed, wind gust, wind direction, pressure, and precipitation. These are created for Home, person-following, device-tracker, and selected-station weather devices, and are disabled by default because the weather.* entities are the primary interface.
• Station metadata is used for Home Assistant device registry entries.
• Weather entities expose observation source diagnostics and forecast station metadata.
• Weather alerts sensor for active Icelandic Met Office CAP weather warnings.
• vedur_is.get_forecast_for_location action for one-off nearest-station forecast lookups by latitude/longitude without creating an entity.
• No API key required.

Installation

HACS Custom Repository

1. Add this repository to HACS as an integration custom repository.
2. Install Icelandic Met Office Weather.
3. Restart Home Assistant.
4. Go to Settings > Devices & services > Add integration and search for Icelandic Met Office Weather.

Manual

Copy custom_components/vedur_is into your Home Assistant config directory at:

config/custom_components/vedur_is

Restart Home Assistant and add the integration from the UI.

Development

Install the lightweight unit-test dependencies:

.venv/bin/python -m pip install -e '.[test]'

Run tests:

.venv/bin/python -m pytest -q

See TODO.md for planned features and follow-up work.

Weather Metadata

Current observations come from the official vedur.is API. When an official API field is unavailable, the integration can fill that field from gottvedur.is page data. Weather entities expose:

• observation_value_sources: maps observation keys such as t, f, fg, and r to official_api, gottvedur_is, or unavailable.
• observation_unavailable_fields: lists observation keys that are still unavailable after fallback data is applied.

Station weather entities also expose forecast metadata:

• station_has_direct_forecast: whether the selected observation station has its own XML forecast.
• forecast_uses_nearby_station: whether forecasts are coming from a nearby forecast-capable station instead of the selected observation station.
• forecast_station_id, forecast_station_name, and forecast_station_distance_km: the forecast station actually used by weather.get_forecasts.

Device tracker weather entities expose device_tracker_entity_id along with the same observation and forecast station metadata. They use the tracker's standard latitude and longitude attributes only; if those attributes are missing, the weather entity is unavailable.

Hourly forecasts come directly from Vedur.is XML forecast time points. Daily and twice-daily forecasts are optional derived summaries made by this integration; when that option is enabled, weather entities add a note to their Home Assistant attribution text.

Station Selection

The integration can help find stations near a place in two ways:

• Search for an Icelandic place name, such as Þórsmörk, then review the map centered on the matched location before selecting nearby stations.
• Pick a location directly on the map and then choose from the nearest stations.

Place search uses the public OpenStreetMap Nominatim search service. Searches are only sent when you submit the form, not while typing, and repeated searches are cached in memory during the Home Assistant process. Forecasts remain station-based; the integration uses the nearest suitable Vedur station rather than a gridded point forecast.

Current Conditions

Weather entity numeric values such as temperature, humidity, dew point, wind, pressure, and precipitation come from current automatic station observations. The Home Assistant condition state, such as sunny, partlycloudy, rainy, or clear-night, comes from the nearest XML forecast time point rather than from the observation API. The observation API does not currently provide a single current-condition text field equivalent to Home Assistant's weather condition state.

One-Off Location Forecasts

Use the vedur_is.get_forecast_for_location action to get the nearest Vedur observation station and XML forecast station for a coordinate without adding a station to the integration.

Example:

action: vedur_is.get_forecast_for_location
data:
  latitude: 64.1466
  longitude: -21.9426
  type: hourly
response_variable: vedur_forecast

Supported forecast types are hourly, daily, and twice_daily. Daily and twice-daily responses are derived summaries, matching the integration's weather entity behavior when derived forecasts are enabled.

The action response includes observation_station, observation, forecast_station, and forecast. Forecasts are still station-based; the integration selects the nearest forecast-capable Vedur station for the coordinate.

API Endpoints Used

• GET https://api.vedur.is/weather/stations?active=true&station_type=sj
• GET https://api.vedur.is/weather/observations/aws/10min/latest?parameters=basic&station_id=<id>
• GET https://xmlweather.vedur.is/?op_w=xml&type=forec&lang=en&view=xml&ids=<ids>
• GET https://gottvedur.is/_next/data/.../en/vedur/athuganir/<station>.json as a fallback for missing current observation values.
• GET https://api.vedur.is/cap/v1/capbroker/active/category/Met plus alert detail payloads for active weather warnings.

API Examples

Fetch the latest processed 10-minute automatic weather observation for station 1470 (Reykjavík):

curl -L "https://api.vedur.is/weather/observations/aws/10min/latest?parameters=basic&station_id=1470"

Pretty-print the same response:

curl -L "https://api.vedur.is/weather/observations/aws/10min/latest?parameters=basic&station_id=1470" \
  | python3 -m json.tool

Fetch parameter metadata for the latest 10-minute observation endpoint:

curl -L "https://api.vedur.is/weather/parameters?url=/observations/aws/10min/latest&locale=en" \
  | python3 -m json.tool

In the basic response, useful current-weather fields include t temperature, rh humidity, td dew point, f wind speed, fg wind gust, d wind direction, p pressure, and r precipitation.

Weather Alerts

The integration creates a sensor.weather_alerts entity. Its state is the number of active Icelandic Met Office weather warning areas. Attributes include the highest warning color and severity, affected areas, and a list of alert details with headline, description, timing, links, and CAP polygon data.

Diagnostic Sensors

Every weather device/location has disabled-by-default diagnostic sensors for its current weather values. Enable only the entities needed by dashboards, automations, or displays that cannot read attributes from a weather.* entity. For example, enabling Wind speed under the Home weather device provides a normal sensor entity suitable for NSPanel displays without a template sensor.

API key	Sensor	Unit
forecast/observation	Condition	Home Assistant weather condition
t	Temperature	Celsius
rh	Humidity	percent
td	Dew point	Celsius
f	Wind speed	m/s
fg	Wind gust	m/s
d	Wind direction	degrees
p	Sea-level pressure	hPa
r	Precipitation, last hour	mm

Null values from the API are represented as unavailable states unless the gottvedur.is fallback provides a value.