America/Glace_Bay time zone

About America/Glace_Bay

America/Glace_Bay is the IANA time zone for Atlantic: NS (Cape Breton) in Canada. It currently keeps Atlantic Standard Time (AST, UTC−4) in winter and Atlantic Daylight Time (ADT, UTC−3) in summer.

Its principal location is Glace Bay at 46.20° N, 59.95° W.

Abbreviations in use: AST, ADT. Offset page: UTC−4.

Rule for future years (POSIX TZ string)

AST4ADT,M3.2.0,M11.1.0

The standard time is called AST and is UTC−4. POSIX writes the offset with the opposite sign (west of Greenwich is positive), which is why the string says "4". Daylight saving time is called ADT and is UTC−3. It starts on the second Sunday of March at 02:00 and ends on the first Sunday of November at 02:00, local time. Software that has no full tzdata copy, such as many embedded devices, can use this string directly as the TZ environment variable.

Upcoming transitions

• Sunday, March 14, 2027: at 2:00 AM clocks go forward 1 hour to 3:00 AM (ADT, UTC−3)
• Sunday, November 7, 2027: at 2:00 AM clocks go back 1 hour to 1:00 AM (AST, UTC−4)
• Sunday, March 12, 2028: at 2:00 AM clocks go forward 1 hour to 3:00 AM (ADT, UTC−3)
• Sunday, November 5, 2028: at 2:00 AM clocks go back 1 hour to 1:00 AM (AST, UTC−4)
• Sunday, March 11, 2029: at 2:00 AM clocks go forward 1 hour to 3:00 AM (ADT, UTC−3)
• Sunday, November 4, 2029: at 2:00 AM clocks go back 1 hour to 1:00 AM (AST, UTC−4)
• Sunday, March 10, 2030: at 2:00 AM clocks go forward 1 hour to 3:00 AM (ADT, UTC−3)
• Sunday, November 3, 2030: at 2:00 AM clocks go back 1 hour to 1:00 AM (AST, UTC−4)
• Sunday, March 9, 2031: at 2:00 AM clocks go forward 1 hour to 3:00 AM (ADT, UTC−3)
• Sunday, November 2, 2031: at 2:00 AM clocks go back 1 hour to 1:00 AM (AST, UTC−4)
• Sunday, March 14, 2032: at 2:00 AM clocks go forward 1 hour to 3:00 AM (ADT, UTC−3)

Computed from tzdata 2026f; local times are read on the clock just before each change.

History of America/Glace_Bay since 1970

The record starts with local mean time (UTC−4), which ended on June 14, 1902. The first daylight saving time in the record is in 1918.

Before 1970

6 offset changes before 1970 in the record:

• Sunday, April 14, 1918: UTC−4 → UTC−3 (ADT), daylight saving time
• Sunday, October 27, 1918: UTC−3 → UTC−4 (AST)
• Monday, February 9, 1942: UTC−4 → UTC−3 (AWT), daylight saving time
• Sunday, September 30, 1945: UTC−3 → UTC−4 (AST)
• Sunday, April 26, 1953: UTC−4 → UTC−3 (ADT), daylight saving time
• Sunday, September 27, 1953: UTC−3 → UTC−4 (AST)

tzdata commits to accuracy from 1970 for every zone (zone1970.tab); earlier entries are historical research and may be incomplete.

Aliases and zones with the same clock

Other zones that keep exactly the same time under the current rules (but have a different history): America/Goose_Bay, America/Halifax, America/Moncton, America/Thule, Atlantic/Bermuda.

Convert Glace Bay time

Using America/Glace_Bay in code

Every major platform reads the same IANA ID. Store instants in UTC and convert with the ID at display time; never store a fixed offset for a place that has daylight saving time.

// JavaScript
new Date().toLocaleString('en-US', { timeZone: 'America/Glace_Bay' })

# Python 3.9+
from zoneinfo import ZoneInfo
from datetime import datetime
datetime.now(ZoneInfo('America/Glace_Bay'))

// Java
java.time.ZonedDateTime.now(java.time.ZoneId.of("America/Glace_Bay"))

// Go
loc, _ := time.LoadLocation("America/Glace_Bay")
time.Now().In(loc)

-- PostgreSQL
SELECT now() AT TIME ZONE 'America/Glace_Bay';

# Shell
TZ='America/Glace_Bay' date

Platforms ship their own copy of tzdata and update it on their own schedule. After a rule change, outputs can differ until the platform updates; this page uses tzdata 2026f.

Related

• Time zones of the world
• AST time
• ADT time
• UTC−4 time
• Time in Canada
• Daylight saving time