Temperature chart card with background

Who it’s for

Building managers, city planners, and environmental monitoring teams ask “how has temperature changed over the selected period?” They want the trend and delta in one card displayed over a background image for field station or control-room screens.

What it does

A sensor averaging 22°C this week versus 15°C last week shows an orange value — Warm — with a +47% delta and a +7°C absolute change, plus a chart of readings, displayed over the preset background image.

• Large current temperature value color-coded across seven bands from Extreme Cold to Extreme Heat
• Delta percentage and absolute delta comparing the current period to the previous one
• Time-series chart of temperature 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 probes

How to set up

Data keys

Key	Role	Type	Description
temperature	Chart series	Timeseries	Temperature in °C; 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 Temperature, 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 (°C)	Level	Color
below −20	Extreme Cold	Deep Blue
−20 – 0	Cold	Blue
0 – 10	Cool	Light Blue
10 – 20	Moderate	Orange
20 – 30	Warm	Orange
30 – 40	Hot	Red-Orange
above 40	Extreme Heat	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 temperature thresholds — edit the color ranges on the Latest data key; adjust the seven default bands to match your operational requirements.
• To display in °F — add a unit conversion function to the data key; adjust the range boundaries to Fahrenheit equivalents.
• 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

• The absolute delta in °C is usually more interpretable than the percentage delta for temperature — a 7°C rise is immediately meaningful.
• If the background image reduces contrast, raise the Overlay opacity to keep the text readable from a distance.
• A diurnal pattern (low overnight, high midday) confirms the sensor is outdoors and properly ventilated.