4 Tips to Level Up Your Date and Time Data

Date and time data are essential for analyzing patterns and events over time. Understanding how ArcGIS Online stores and displays temporal data is key, whether you’re tracking population changes, weather events, or wildlife observations. In this article, we’ll explore field types and settings that give you greater insight and more control over your temporal data.

• Tip #1: Choose the Right Fields
• Tip #2: Set the Web Map Time Zone
• Tip #3: Preserve the Time Zone of the Data
• Tip #4: Adjust for Daylight Savings Time

How ArcGIS Online stores and displays time

there are some universal truths to keep in mind when using a standard Date field in ArcGIS:

• Values are stored in UTC.
• If no time is entered, a default time of 12:00 AM (midnight) is automatically assigned.
• Values shown in popups and tables get adjusted to the viewer’s device time zone.

This ensures that ArcGIS Online shows event times in your local time zone. But it can sometimes lead to unexpected results. For example, January 1, 2024, at 12:00 AM in New York appears as December 31, 2023, at 10:00 PM in the Mountain time zone. If not expected, this could impact analysis, or just leave you wondering what happened. In the following sections, we’ll share tips to help you gain greater understanding and control over dates and times in ArcGIS Online.

Glossary

• Device time- the time zone of the device on which you are reading this article. Usually its the time zone where you’re located.
• DST- Daylight savings time
• UTC – Coordinated Universal Time, or UTC, is the time standard used across the globe. It is effectively Greenwich Mean Time (GMT).

Tip #1: Choose the right fields

ArcGIS now offers four temporal field types. Choose the right one to meet your needs:

• Date: Stores both date and time together. Always.
• Date only: Stores dates without times, ideal when time is irrelevant.
• Time only: Stores times without dates, useful for schedules and business hours.
• Timestamp offset: Stores date, time, and the time zone offset from UTC, great for data collected across multiple time zones.

For more information on when to use each field type, check out the article New Field Types in ArcGIS Online.

Tip #2: Set the web map time zone

In Map Viewer, you can set a time zone in the Map properties. This gives you more control over how date and time values are displayed across devices.

Select one of the following:

1. Device time zone: The date and time values are adjusted based on each viewer’s device.
2. Specific time zone: The values display in a specified time zone regardless of device time.
3. Data’s time zone: Displays the date and time as-is, without adjusting for location. If the layer has a time zone set on it (see tip #3), that will persist under this setting.

For a deeper dive into web map time zones, check out this article.

Tip #3: Preserve the Time Zone

Time zone information can be preserved in a couple of ways:

• Set it at the layer level when publishing data.
• Set it the feature level using the Timestamp offset field.

Layer level

At publishing time, you can set a time zone for the layer. This is handy when A) all of the data was collected in the same time zone, and B) you want to preserve the time zone information with the layer. Note: If you don’t specify a time zone at publishing time, it defaults to UTC.

Feature level

Different time zones can be saved for different features using the Timestamp offset field. This is especially useful for global data sets since you can set the date, time, and time zone for each feature.

Tip #4: Adjust for Daylight Savings Time

When publishing a layer from ArcGIS Pro, you can adjust for daylight savings time (DST). With the setting enabled, the date and time values are automatically adjusted, forward or back, based on when daylight savings time starts or ends.

Strategies for locking down date and time values

Example 1: Use the right field type

Imagine you’re using a Date field and enter only a date, but no time. You’ll notice a time is added. That’s because Date fields always store both a date and a time. If no time is provided, ArcGIS automatically assigns 12:00 AM (midnight). Tip: If time isn’t important, use a Date only field.

Example 2: Prevent date time adjustments

As you’ve seen, values in Date fields are stored in UTC, and display according to the viewer’s device time zone. While this is often helpful, it can sometimes produce unexpected results. For example, a value entered as 1/1/2023 12:00 am viewed on a device in a time zone 1 hour behind is displayed as 12/31/2022 11:00 pm.

The time, the date, and even the year changed, or rather, the way they display was adjusted. Tip: use a Date only field, or set a web map time zone so dates and times display consistently.

Summary

In this article, we explored universal truths and data management strategies to help you level up your date and time data management powers in ArcGIS Online. You can choose from diffferent approaches based on your data needs and goals. Mapping and editing temporal data can be tricky, but having the right understanding and helpful tools can make it easier. By leveraging features such as field types, web map time zones, and layer publishing options, you can gain greater control over how dates and times are stored and displayed across ArcGIS Online.

ArcGIS Online Help has a wealth of information on working with date and time data. And be sure to join the conversation on Esri Community where you can ask questions, connect with other ArcGIS Users and share your own insights.