Visibility card

Who it’s for

Road safety managers, airport operations teams, and port and harbor controllers ask “is atmospheric visibility safe for traffic and navigation right now?” They need an immediate reading that signals whether conditions have dropped below the threshold for speed restrictions, low-visibility procedures, or vessel movement rules.

What it does

A sensor reading 2.5 km shows an orange value — Moderate — indicating reduced but not yet operationally critical visibility. The same card shows green at 8 km — Good — and red at 0.3 km — Poor.

• Large current visibility value color-coded across three bands from Poor to Good
• Color-coded icon matching the value band so the status is visible at a glance
• Last-updated timestamp showing how long ago the reading arrived
• Shows one sensor’s data; it does not chart visibility trends or compare multiple sensors

How to set up

Data keys

Key	Role	Type	Description
visibility	Main value	Timeseries	Atmospheric visibility distance (km); change the key name to match your device’s telemetry key

The widget ships with a simulated function datasource key labeled Visibility, so it draws random values until you point the datasource at a device and rename the key.

To point it at your own device: open the dashboard in edit mode, open the widget’s Datasources, pick the entity or entity alias, and replace the function key with the key your device reports.

The card shows the value with one decimal place. If the key has never reported, the card displays the label and icon with an empty value, not an error.

Value ranges

Range (km)	Level	Color
0–1	Poor	Red
1–4	Moderate	Orange
4+	Good	Green

How to customize

• To use your own visibility thresholds — edit Icon color ranges and Value color ranges; set the same boundaries in both so the icon and the number always agree.
• To change the icon — set Icon to any Material or MDI icon name.
• To hide the label, icon, or timestamp — turn off Show label, Show icon, or Show date.
• To switch to an absolute timestamp — turn off Last update ago in the date format settings.
• To match your dashboard’s fonts — set Value font and Label font.

Tips

• Poor visibility below 1 km corresponds to the ICAO threshold for low-visibility procedures at airports and is the common trigger for reduced speed limits on motorways during fog events; adjust the Poor/Moderate boundary to match your local regulation.
• Fog typically forms when visibility drops quickly overnight while relative humidity approaches 100% — pair with a humidity card to distinguish fog from dust or haze events.
• A rapid improvement from Poor to Good within minutes usually indicates wind picking up or solar heating burning off ground fog; a slow climb over several hours suggests the fog is lifting through its full depth.