Temperature chart card

Who it’s for

Building managers, city planners, and environmental monitoring teams ask “how has temperature changed over the selected period, and how does this week compare to last?” They want the current reading, the trend, and the delta in one card so they can judge whether conditions are improving, worsening, or holding steady.

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 over the selected window.

• 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
• 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 use your own temperature thresholds — edit the color ranges on the Latest data key; adjust the seven default bands to match your operational or comfort 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.
• To match your dashboard’s fonts — set the font options under each data key’s appearance settings.

Tips

• The absolute delta in °C is usually more interpretable than the percentage delta for temperature — a 7°C rise is immediately meaningful, while a +47% change requires knowing the baseline.
• Use this card alongside a humidity chart card to track apparent temperature (heat index) trends during summer heatwaves or cold snaps.
• A diurnal pattern (low overnight, high midday) confirms the sensor is outdoors and properly ventilated; a flat 24-hour line suggests the sensor may be shielded or indoors.