Date-time group (DTG)
Also written: DTG, Zulu time
A compact UTC timestamp — day, hour and minute followed by Z — such as 201500Z for the 20th at 15:00 UTC.
Warnings write times as date-time groups: two digits for the day of the month, four for the time, and the letter Z for UTC ("Zulu" time), usually followed by the month and year — 201500Z APR 26 is 20 April 2026 at 15:00 UTC. Activity windows, cancellation times and the time a report was received are all written this way.
Because the month and year can be left out when they are obvious to the reader at the time, the same group can be ambiguous years later. seahazards reads windows against the warning's own issue date for that reason.
What the archive shows
107,280 messages in this archive use “Date-time group (DTG)”, the earliest issued 1987-03-20 and the latest 2026-09-24. 79 of them are in force in the latest lists we collected. A hazard reported again and again counts once per message.
The largest yearly count is 2023, with 6,757 messages. Collection is incomplete between 2024-05 and 2026-08-17, so 2024, 2025 and 2026 are not comparable with fully collected years.
Exercises accounts for 33,742 of 107,280 recorded messages (31%), the largest warning type group in this selection.
Located messages that use it fall in 97 sea areas; the most frequent are North Pacific Ocean (12,123), South Atlantic Ocean (10,221) and North Atlantic Ocean (8,775).
Its use is spread fairly evenly through the year: the busiest month, March, has 9,680 messages and the quietest, February, 8,089.
By warning series: HYDROPAC 42,010, HYDROLANT 33,127, USGS 13,049 and NAVAREA IV 11,141, and 9 more.
Messages using it, by year of issue
By month of issue, all years
Where it appears · 97 sea areas
- North Pacific Ocean 12,123
- South Atlantic Ocean 10,221
- North Atlantic Ocean 8,775
- South Pacific Ocean 7,135
- South China Sea 4,560
- Indian Ocean 4,298
- Labrador Sea 3,683
- Arabian Sea 3,354
- Philippine Sea 3,269
- Bay of Bengal 3,130
- Mediterranean Sea - Eastern Basin 3,089
- Southern Ocean 3,059
In force now · 79
- JTWC-EP1726 · Storms · North Pacific Ocean2026-09-24 · in force
EASTERN NORTH PACIFIC. HURRICANE 17E (POLO). 1. JTWC WARNING NUMBER 15 ISSUED 241000Z SEP 26. FORECAST POSITION 16.400N 103.000W. 2. 34-KNOT WIND DANGER SWATH SHOWN. 3. JOINT…
Hurricane 17E (polo) → - JTWC-WP2526 · Storms · Philippine Sea2026-09-24 · in force
WESTERN NORTH PACIFIC. TROPICAL STORM 25W (SURIGAE). 1. JTWC WARNING NUMBER 05 ISSUED 240900Z SEP 26. FORECAST POSITION 18.900N 133.100E. 2. 34-KNOT WIND DANGER SWATH SHOWN. 3. JOINT…
Tropical storm 25W (surigae) → - NHC-EP172026 · Storms · North Pacific Ocean2026-09-24 · in force
EASTERN NORTH PACIFIC. HURRICANE POLO (EP172026). 1. CENTER NEAR 16.500N 103.500W AT 240900Z SEP 26, MAXIMUM SUSTAINED WINDS 140 KT, MINIMUM PRESSURE 923 MB, MOVING 310 DEGREES AT 9…
Hurricane polo (EP172026) → - NHC-EP162026 · Storms · North Pacific Ocean2026-09-24 · in force
EASTERN NORTH PACIFIC. HURRICANE ODALYS (EP162026). 1. CENTER NEAR 16.100N 126.000W AT 240900Z SEP 26, MAXIMUM SUSTAINED WINDS 75 KT, MINIMUM PRESSURE 978 MB, MOVING 60 DEGREES AT 8…
Hurricane odalys (EP162026) → - NAVAREA XI 426/26 · Cable ops · South China Sea2026-09-24 · in force
…OCT 2026. IN VICINITY OF A.11-38.23N 118-56.36E. B.11-34.10N 118-53.54E. CANCEL THIS MSG 091600Z OCT.
Submarine pipeline works by M/V fortitude → - USGS-US6000TX3M · Quakes · South Pacific Ocean2026-09-23 · in force
…OF HIHIFO, TONGA. 1. EARTHQUAKE MAGNITUDE 5.7 (MWW) IN 14.937S 175.111W, DEPTH 10 KM AT 231441Z SEP 26. 2. USGS EVENT US6000TX3M.…
180 km nw of hihifo, tonga →
How it reads in recent messages
- NHC-AL062026 · Storms · North Atlantic Ocean2026-09-24
ATLANTIC. TROPICAL STORM FAY (AL062026). 1. CENTER NEAR 29.800N 040.500W AT 240900Z SEP 26, MAXIMUM SUSTAINED WINDS 35 KT, MINIMUM PRESSURE 1010 MB, MOVING 270 DEGREES AT 7…
Tropical storm fay (AL062026) → - NHC-EP152026 · Storms · North Pacific Ocean2026-09-24
EASTERN NORTH PACIFIC. TROPICAL STORM NOLO (EP152026). 1. CENTER NEAR 14.900N 156.000W AT 240900Z SEP 26, MAXIMUM SUSTAINED WINDS 45 KT, MINIMUM PRESSURE 999 MB, MOVING 360 DEGREES AT 2…
Tropical storm nolo (EP152026) → - JTWC-IO0126 · Storms2026-09-24
…OCEAN. TROPICAL CYCLONE 01B (ONE). 1. JTWC WARNING NUMBER 06 (FINAL WARNING) ISSUED 240300Z SEP 26. FORECAST POSITION 18.100N 083.700E. 2. 34-KNOT WIND DANGER SWATH SHOWN. 3. JOINT…
Tropical cyclone 01B (one) →
Earliest in the archive
- NOAAORR-6456 · Spills · Gulf of Alaska1987-03-20
F/V Miss Leona; Mitrofania Island, Alaska. Mitrofania Island, Alaska. 1. 1. AT APPX. 201757Z MAR87 SUBJ VSL REPORTED ITSELF DISABLED AND ADRIFT AT POSIT. 5542N, 15843W, 6-7 MILES SE…
Mitrofania island, alaska →
Often in the same message
Related terms
- CANCEL THIS MSG
- The warning's own expiry: a line telling the reader when the message cancels itself.
- Until further notice
- The operation or danger has no scheduled end; the warning stays in force until a later message cancels it.
Counts cover the messages in this archive that use the term, recounted 2026-09-24; see coverage for what is collected and since when. Not for navigation — follow official NAVAREA and coastal broadcasts.