Time Zone History

Pituffik (Thule) time zone history

Seasonal clock changes began only in 1991 and are still in use. Pituffik (Thule) kept local mean time (UTC−4:35:08) until 1916, the latest switch of the 19 zones on UTC−4 standard time. On standard time, clocks at Pituffik (Thule) run 35 minutes ahead of local mean solar time, the third-largest gap of the 14 zones on UTC−4 standard time whose clocks run ahead of the sun.

UTC−4

Standard time is UTC−4 (ADT/AST); clocks go forward to UTC−3 on the second Sunday in March and back on the first Sunday in November.

Covers: Thule/Pituffik · tz database name America/Thule

Convert a time from Pituffik (Thule)

Summer time in 36 of 57 years since 1970

UTC−4:35:08: 35 minutes behind today’s standard timeUTC−4: today’s standard timeUTC−3: 1 hour ahead of today’s standard timeUTC−4:35:08: 35 minutes behindtoday’s standard timeUTC−4: today’s standard timeUTC−3: 1 hour ahead of today’sstandard time

How to read this chart

Before 1970

19101920193019401950196019701910192019301940195019601970
JanFebMarAprMayJunJulAugSepOctNovDec1970198019902000201020202028JFMAMJJASOND1970198019902000201020202028

Standard time changes

DateChangeNew standard timeClock label
Before 1970
July 28, 1916Local mean time (UTC−4:35:08) replacedUTC−4AST

Daylight saving periods

YearsClocks go forwardClocks go backShift and labels
1991–1992last Sunday in March, 02:00last Sunday in September, 02:001 hour, AST to ADT
1993–2006first Sunday in April, 02:00last Sunday in October, 02:001 hour, AST to ADT
2007–2037second Sunday in March, 02:00first Sunday in November, 02:001 hour, AST to ADT

Clock changes in 2026, 2027 and 2028

The clocks go forward 1 hour (AST to ADT) on March 8, 2026, March 14, 2027 and March 12, 2028 at 02:00 and back 1 hour (ADT to AST) on November 1, 2026, November 7, 2027 and November 5, 2028 at 02:00, local time.

Also on UTC−4

Goose Bay (Canada), Moncton (Canada), Glace Bay (Canada), Halifax (Canada), Bermuda, Dominican Republic, Puerto Rico, Martinique, Barbados and Venezuela (nearest first; 8 more on the list of offsets).

Clocks next door since 1970

  • Resolute (Canada) (741 km): usually 2 hours behind; different on 3,953 days in 1972–2026.
  • Danmarkshavn (1,247 km): usually 1 hour ahead; different on 13,460 days in 1980–2026; 4 hours ahead today.
  • Cambridge Bay (Canada) (1,413 km): usually 3 hours behind; different on 4,187 days in 1972–2026.
  • Iqaluit (Canada) (1,427 km): usually 1 hour behind; different on 4,027 days in 1972–2026.
  • Nuuk (1,503 km): usually 1 hour ahead; different on 3,685 days in 1980–2026; 2 hours ahead today.

How it compares

Standard time has stayed at UTC−4 since 1916.