Rainfall chart card

Who it’s for

Farmers, city flood managers, and environmental monitoring teams ask “how has rainfall changed over the selected period, and are totals rising or falling compared to the previous period?” They want the current reading, a trend line, and a period-over-period delta in one card to plan irrigation and drainage responses.

What it does

A sensor averaging 4.2 mm this week versus 1.0 mm last week shows a dark-blue value — Moderate — with a +320% delta and a +3.2 mm absolute change, plus a chart of readings over the period.

• Large current rainfall value color-coded across four bands from None to Heavy
• Delta percentage and absolute delta comparing the current period to the previous one
• Time-series chart of rainfall readings averaged per interval
• Shows one sensor’s data; it does not compare multiple gauges

How to set up

Data keys

Key	Role	Type	Description
rainfall	Chart series	Timeseries	Precipitation in mm; 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 Rainfall, 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 (mm)	Level	Color
0	None	Light Blue
0–2.5	Light	Medium Blue
2.5–7.6	Moderate	Dark Blue
7.6+	Heavy	Deep Blue

How to customize

• To use your own rainfall thresholds — edit the color ranges on the Latest data key; adjust the four default bands to match your operational or agronomic 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 show min, max, or total in the legend instead of avg — edit the Legend settings; total is often the most useful aggregation for rainfall.
• To hide the entity name subtitle or the timestamp — turn off Show subtitle or Show date.

Tips

• Switch the legend aggregation to total if you want cumulative rainfall for the period rather than the average rate per interval.
• Use this card when the period-over-period change matters. If you only need the trend shape without a delta, use the simple rainfall chart card instead.