Central Daylight Time (CDT)

UTC offset: -05:00 (during DST)
Standard offset: -06:00 (CST)
IANA identifier: America/Chicago
Abbreviation: CDT
Population: approximately 90 million (US + Canada in this zone)
DST period: Second Sunday in March to first Sunday in November

Central Daylight Time advances North America's central time zone one hour from CST (UTC-06:00) to UTC-05:00 during the warmer months. The zone covers the American heartland from Texas to Wisconsin, parts of Canada (Manitoba, Saskatchewan border regions), and historically Mexico City (though Mexico's central zone now has different DST dates or none).

CDT is the second-most-populous US time zone after Eastern. Chicago, Dallas-Fort Worth, Houston, San Antonio, and the Twin Cities all operate here. During CDT, the Central zone sits one hour behind Eastern (EDT, -04:00) and one hour ahead of Mountain (MDT, -06:00).

Major Cities

• Chicago (~2.7M city, ~9.5M metro): Third-largest US city. Finance (CME Group, futures/options), transportation hub (O'Hare), architecture, and deep-dish pizza.
• Houston (~2.3M city, ~7M metro): Energy capital (oil/gas headquarters), NASA Johnson Space Center, the Port of Houston (largest US port by tonnage).
• Dallas-Fort Worth (~7.6M metro): Technology, telecom (AT&T), defense, logistics. DFW Airport is a major international hub.
• San Antonio (~1.5M city): Military (Joint Base San Antonio), healthcare, tourism (Alamo, River Walk).
• Minneapolis-St. Paul (~3.7M metro): Finance, medical devices (Medtronic, Mayo Clinic nearby), grain trading.

Geographic Scope (US)

From the Gulf Coast to the Canadian border:

• Texas (most of it), Louisiana, Mississippi, Alabama (western), Tennessee (western), Arkansas, Missouri, Oklahoma, Kansas, Nebraska, Iowa, Minnesota, Wisconsin, Illinois, Indiana (western counties), North Dakota, South Dakota

The zone boundary isn't always on state lines. Several states are split (Indiana's complexities are legendary).

Canada

• Manitoba (Winnipeg, ~750,000): The only fully-Central province. Same DST schedule as the US.
• Saskatchewan officially uses CST year-round (no DST), making it CDT in winter alignment terms but out of sync in summer.
• Ontario (western): Thunder Bay area.

Mexico

Mexico City used CDT until 2022, when Mexico abolished DST for most of the country. The northern border municipalities still observe US-aligned DST to avoid confusion at the border. This creates a patchwork in Mexico's central zone.

Scheduling

At UTC-05:00 (CDT):

• Eastern (EDT, -04:00): 1 hour ahead
• Mountain (MDT, -06:00): 1 hour behind
• Pacific (PDT, -07:00): 2 hours behind
• London (BST, +01:00): 6 hours ahead
• Tokyo (+09:00): 14 hours ahead

Climate Diversity

The CDT zone spans enormous climate variation:

• Gulf Coast (Houston): Subtropical, hot humid summers (35C+), mild winters
• Great Plains (Kansas, Nebraska): Continental, severe thunderstorms, tornadoes
• Upper Midwest (Minneapolis): Cold continental, -30C winter extremes, warm summers
• Texas interior: Semi-arid to arid, extreme heat

Technical Identifiers

• America/Chicago (IANA canonical)
• America/Winnipeg (IANA, Manitoba)
• CDT (Central Daylight Time)
• Windows: "Central Standard Time"
• DST rule: US (2nd Sunday March to 1st Sunday November)
• Mexico border zones: still observe US-aligned DST

Quick Reference