Amazon Web Services (AWS) has an established maintenance window that occurs weekly at the following times based on your location and time zone:
Australia and New Zealand (Sydney, AU datacenter): Monday 18:00-18:30 UTC (GMT)
APAC excluding Korea, Australia, and New Zealand (Singapore datacenter): Monday 20:00-20:30 UTC (GMT)
Korea (Korean datacenter): Monday 19:00 - 19:30 UTC (GMT)
EMEA (Frankfurt datacenter): Tuesday 1-1:30 UTC (GMT)
North America, Central America, South America (US East, GovCloud and Canadian datacenters): Tuesday 08:00-08:30 UTC (GMT)
The standard maintenance window is a maximum of 30 minutes. Work may or may not happen during this window. Typically work performed during this window takes less than 30 minutes (while our highly available components failover across avail zones). During the maintenance window, AWS performs work on clusters and instances in batches and our processes failover active clusters and instance to a different availability zone. For example, RDS and or Infrastructure changes may occur and take 30 seconds to complete, and batch one starts at minute one and batch two starts at minute two.
For the security and stability of your environment, maintenance can cause instances to be briefly unavailable.
If you have any questions in regards to the AWS Maintenance window, please contact Support at 888-788-5264.