Why Should You Avoid Scheduling Snowflake Tasks Between 1 AM and 3 AM on Sundays?

Snowflake TasksDaylight Saving Time (DST) may bring to mind images of brighter evenings or the age-old adage “spring forward, fall back.” But for Snowflake administrators and users, the semi-annual ritual of adjusting the clock may also entail unforeseen task executions. Snowflake, the leading cloud-based data warehousing platform, recommends avoiding the scheduling of tasks between 1 AM and 3 AM on Sundays specifically because of DST changes. Let’s delve into why this recommendation is crucial and what alternatives you have to ensure smooth operations.

The Intricacies of Time-Driven Tasks

In any data warehousing environment, task scheduling plays a vital role. Regularly scheduled tasks might include data updates, maintenance tasks, or analytical jobs that are set to run at off-peak hours to conserve resources. While scheduling seems straightforward, there are external factors, like Daylight Saving Time, that can create unexpected outcomes.

The Issue with Daylight Saving Time

Daylight Saving Time starts on the second Sunday of March, at which point clocks are set forward by one hour at 2 AM local standard time, which becomes 3 AM local daylight time. Conversely, it ends on the first Sunday in November, when clocks are set back one hour at 2 AM local daylight time, which becomes 1 AM local standard time.

If you have tasks scheduled to run between 1 AM and 3 AM on Sundays, they could either execute twice or not execute at all during these time changes. This could lead to duplicated data, missed updates, or even system errors that could be hard to debug later.

Snowflake’s Recommendation

To sidestep these potential problems, Snowflake advises not to schedule tasks during this time frame on Sundays. By doing so, you eliminate the risk of unexpected task executions and ensure that your data workflows remain reliable and accurate.

Alternative Approaches

However, if your operations absolutely require tasks to be scheduled during these hours, there’s an additional safeguard you can apply:

  • Manual Checks: On the two Sundays in a year when DST starts or ends, manually review and adjust your task schedules. This involves extra work and attention to detail but will help to maintain the accuracy and reliability of your system.


Time is a fickle thing, especially when we manipulate it ourselves for the sake of Daylight Saving Time. Snowflake’s recommendation to avoid scheduling tasks between 1 AM and 3 AM on Sundays is a best practice that aims to protect the integrity of your data warehousing operations. Although it may seem like a minor detail, following this recommendation could save you significant time and effort in debugging and problem-solving down the line.

If you cannot avoid scheduling tasks during these hours, be prepared to perform manual checks twice a year. Either way, awareness and planning are key to navigating the intricacies of time-driven tasks in Snowflake, especially when the clocks are set to change.

How Anyon Consulting Can Help

Navigating the complexities of task scheduling around Daylight Saving Time changes can be challenging, even for seasoned Snowflake users. This is where Anyon Consulting can step in to assist you. Our team of experts can help you audit your existing task schedules, identify potential pitfalls related to Daylight Saving Time, and implement best practices to ensure seamless operations. We offer comprehensive solutions that not only solve immediate issues but also future-proof your Snowflake environment against unexpected disruptions. Don’t let something as seemingly trivial as a clock change throw a wrench in your data operations; reach out to Anyon Consulting today for a consultation.

Scroll to top