AWS Cron Expression — EventBridge & CloudWatch Syntax

AWS EventBridge (formerly CloudWatch Events) uses a modified cron syntax with 6 fields instead of the standard 5:

minute hour day-of-month month day-of-week year

Key differences from standard cron:

• Year field: AWS adds a mandatory year field (use * for every year)
• ? wildcard: AWS requires ? (no specific value) in either the day-of-month or day-of-week field — you can't use * in both
• No @shortcuts: AWS doesn't support @daily, @hourly, etc.
• UTC only: All AWS cron expressions run in UTC

Example: 0 12 * * ? * runs every day at noon UTC. The ? in the day-of-week field means "no specific day of week" since we already specified * for day-of-month.

Common AWS cron patterns:

• Every 5 minutes: */5 * * * ? *
• Every day at midnight UTC: 0 0 * * ? *
• Every Monday at 9 AM UTC: 0 9 ? * 2 * (AWS uses 1=Sunday, 2=Monday)