UV Index chart card with background

Who it’s for

Public health managers, outdoor venue operators, and school safety coordinators ask “how has the UV index changed over the selected period?” They want the trend and delta in one card displayed over a background image for field station or public-display screens.

What it does

A sensor averaging 6 this week versus 3 last week shows an orange value — High — with a +100% delta and a +3 absolute change, plus a chart of readings, displayed over the preset background image.

• Large current UV index value color-coded across five bands from Low to Extreme
• Delta percentage and absolute delta comparing the current period to the previous one
• Time-series chart of UV index readings averaged per interval
• Decorative background image bundled with the widget, with a white overlay that keeps the text readable
• Shows one sensor’s data; it does not compare multiple sensors

How to set up

Data keys

Key	Role	Type	Description
uv	Chart series	Timeseries	UV index (dimensionless); drives the chart and all derived overlays
Latest	Latest value	Timeseries	The headline figure above the chart. Its own color ranges are where the band colors are edited
Delta percent	Percentage change	Timeseries	Change against the previous period, as a percentage
Delta absolute	Absolute change	Timeseries	Change against the previous period, in the key’s own unit

The widget ships with a simulated function datasource key labeled UV Index, 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.

If the key has never reported for the selected time window, the chart is empty and all overlays show no data.

Value ranges

Range	Level	Color
0–2	Low	Green
2–5	Moderate	Orange
5–7	High	Orange
7–10	Very High	Red-Orange
10+	Extreme	Red

How to customize

• To swap the background image — open the widget settings and set Background to a different image or switch to a solid color.
• To adjust how much the background shows through — change the Overlay opacity; lower values reveal more of the image, higher values push it further back.
• To use your own UV thresholds — edit the color ranges on the Latest data key; adjust the five default bands to match your advisory thresholds.
• To change the comparison period — adjust the Time window on the dashboard; the delta automatically compares to the equivalent preceding period.
• To hide or show the chart — toggle Show chart in the widget settings.
• To change the chart line color — set Chart color.
• To hide the entity name subtitle or the timestamp — turn off Show subtitle or Show date.

Tips

• A week-over-week positive delta in spring is expected as solar angle increases; a sudden spike mid-summer may indicate unusual atmospheric conditions.
• If the background image reduces contrast, raise the Overlay opacity to keep the text readable from a distance.
• Pair with a solar radiation chart card: high UV with relatively lower irradiance can occur under scattered cloud, which still poses a sunburn risk.