Does AWS remove old events from health API ?

Hello.

The following documentation states that health events can be viewed on the AWS Health Dashboard or the AWS Health API for up to 90 days.
https://repost.aws/knowledge-center/health-events-dashboard

You can use the AWS Health Dashboard to view the health of all AWS services. Health events (public or account-specific) might request you to act on resources in your AWS account. For example, stopping an Amazon Elastic Compute Cloud (Amazon EC2) instance that has scheduled maintenance. You can review the event description to understand the issue, identify affected resources, and follow the requested actions. The event status tells you if the Health event is open, closed, or upcoming. You can view Health events in the AWS Health Dashboard, or the AWS Health API, for up to 90 days.

Yes, AWS does remove old events from the AWS Health API after a certain period. For most AWS Health events, including those visible through the organizational view, the retention period is 90 days. After this time, the events are automatically deleted and are no longer accessible through the API.

When you're working on an internal dashboard for AWS service health, it's important to note that you won't be able to retrieve data older than 90 days using the AWS Health API. This explains why you're unable to find the past data that you pulled in January if it's now been more than 90 days.

To maintain a longer history of health events for your internal dashboard, you should consider implementing a solution to store the data you retrieve from the AWS Health API. Some options include:

1. Regularly pulling data from the AWS Health API and storing it in your own database or data store.
2. Using Amazon EventBridge to capture AWS Health events and store them in a CloudWatch log group or an S3 bucket for longer-term retention.
3. Setting up a custom solution using AWS Lambda to periodically fetch health data and store it in a persistent storage service like Amazon S3 or Amazon DynamoDB.

By implementing one of these approaches, you can maintain a historical record of AWS Health events beyond the 90-day limit provided by the AWS Health API, ensuring that your internal dashboard can display both recent and historical data.
Sources
Viewing organizational view - AWS Health
Aggregating AWS Health events across accounts - AWS Health

You can also use a custom action with an EventBridge rule to store the findings in an S3 bucket (if you want to retain more than 90 days of findings).

https://docs.aws.amazon.com/pdfs/health/latest/ug/awshealth-ug.pdf

The above is a good answer, with one exception. All Planned Lifecycle Events are held for 4 years past the date of impact.