CDT time now (Central Daylight Time)

What CDT means

CDT stands for Central Daylight Time, UTC−5. It is used in the central United States and parts of Canada and Mexico.

It is a summer time: the daylight saving form of CST (UTC−6), one hour ahead. In Chicago it applies from March to October/November: from the second Sunday of March at 2:00 AM to the first Sunday of November at 2:00 AM.

CDT is ambiguous. It also means Cuba Daylight Time (UTC−4, Cuba). This page shows UTC−5, the meaning English searchers usually want.

Three different CSTs

CST is one of the most ambiguous abbreviations in use. In North America it is Central Standard Time, UTC−6: Chicago, Dallas, Mexico City and Winnipeg’s old zone. In China it is China Standard Time, UTC+8, used by the whole country (and by Taiwan and Macau under the same letters). Cuba writes CST for Cuba Standard Time, UTC−5. The same three letters cover a 14-hour spread.

Our search data shows that people who type “CST” on an English search engine overwhelmingly mean US Central time, so this page shows UTC−6 first. When you read CST in a message from Asia, check: “CST 9:00” from a colleague in Shanghai is 1:00 UTC, not 15:00 UTC.

CDT has two meanings as well: Central Daylight Time (UTC−5, the US and Canadian summer form) and Cuba Daylight Time (UTC−4). Mexico abolished daylight saving time for most of the country in October 2022, so Mexico City now stays on CST all year. Some municipalities on the US border still follow the US dates: Matamoros and Ojinaga switch between CST and CDT, while Ciudad Juárez and Tijuana use Mountain and Pacific time.

Where and when CDT is used

12 zones use it for part of the year only, switching back to standard time in the other months. Computed from tzdata under the current rules.

Other meanings of CDT

When a time arrives with only these letters, look at where the sender is, or ask for the UTC offset. Calendars and programs should never guess a zone from an abbreviation: the IANA database’s own documentation calls abbreviations ambiguous in practice.

How long CDT has been used

In the tzdata record, Chicago has used CDT since 1918, Knox has used CDT since 1918 and Tell City has used CDT since 1918.

CDT in the past

Zones whose tzdata history shows CDT before 2025 but that no longer use it:

• America/Winnipeg (Winnipeg): 1916–2024
• America/Mexico_City (Mexico City): 1939–2022
• America/Monterrey (Monterrey): 1988–2022
• America/Merida (Mérida): 1996–2022
• America/Bahia_Banderas (Bahia Banderas): 2010–2022
• America/Cancun (Cancún): 1996–2014
• America/Indiana/Petersburg (Petersburg): 1918–2007
• America/Indiana/Vincennes (Vincennes): 1918–2007
• America/Indiana/Winamac (Winamac): 1918–2006
• America/Guatemala (Guatemala City): 1973–2006
• America/Managua (Managua): 1979–2006
• America/Tegucigalpa (Tegucigalpa): 1987–2006

CDT converted to other zones

Every column is a fixed offset, so this table is valid on any date. Remember that the regions behind some columns switch to summer time (EST to EDT, CET to CEST, GMT to BST); the clock in those cities is then an hour later than the column.

Related zones and conversions

• CST time
• America/Chicago time zone
• UTC−5 time
• Time zones of the world
• Daylight saving time
• Time zone converter