Create an Alarm from a Metric on a Graph
You can graph a metric and then create an alarm from the metric on the graph, which has the benefit of populating many of the alarm fields for you.
To create an alarm from a metric on a graph
Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.
If necessary, change the region. From the navigation bar, select the region that meets your needs. For more information, see Regions and Endpoints in the Amazon Web Services General Reference.
In the navigation pane, click Metrics.
In the CloudWatch Metrics by Category pane, select a category to view available metrics.
Select the check box next to the metric for which you want to create an alarm.
In the details pane, under Actions, click Create Alarm, and then complete the alarm fields.
For more information about how to create an alarm, see Creating Amazon CloudWatch Alarms.