Coordinated Universal

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Time Zone: Europe/ Amsterdam: Universal Time Coordinated GMT / UTC: UTC+1: Daylight Saving Time CEST: Central European Summer Time: UTC+2: Standard Time CET: Central European Time. Coordinated Universal Time Local time is based on time zone and Coordinated Universal Time (UTC). UTC is commonly referred to as International Time, Universal Time (UT), Zulu Time (U.S. Military), or Greenwich Mean Time (GMT). GMT was established by international conference in 1884 as. The Zulu term stems from military usage while Coordinated Universal Time is the civilian term for this 24-hour clock. The origin of these time zones began in the mid 1800's in England. In 1852 the Royal Observatory in Greenwich, England began transmitting time telegraphically and just three years later became the standard time in most of Great. Definition of Coordinated Universal Time: the international standard of time that is kept by atomic clocks around the world —abbreviation UTC — compare greenwich mean time, universal time First Known Use of Coordinated Universal Time 1969, in the meaning defined above.

Coordinated universal time

All aspects of meteorology are based upon a world-wide 24-hour clock called Zulu time (Z), more commonly called Coordinated Universal Time (UTC). You will notice all weather maps, radar, and satellite images all have their time expressed in 'Z'. The Zulu term stems from military usage while Coordinated Universal Time is the civilian term for this 24-hour clock.

The origin of these time zones began in the mid 1800's in England. In 1852 the Royal Observatory in Greenwich, England began transmitting time telegraphically and just three years later became the standard time in most of Great Britain. Also, charts and maps were made with reference to the observatory as the 'zero' or prime meridian.

Over the next few decades a number of locations around the world had developed their own meridians as reference points. The Greenwich meridian was the most popular of these in part due to the reputation for reliability and correctness of the Greenwich Observatory's publications of navigational data.

In 1884, a conference in Washington, D.C. settled the matter where it was agreed to establish a single 'prime' meridian (0° longitude), passing through Greenwich. This was for both for longitude and timekeeping. This 0° meridian divides the Eastern from the Western Hemisphere. Today, one can visit the Royal Observatory and straddle this 0° meridian with one foot in each hemisphere.

With the 360° daily rotation of the earth, the sun is moving 15° each hour which leads to the formation of 24 time zones. However, today the individual zone boundaries are no longer straight, nor are they always continuous, as they have been modified for convenience and to satisfy the desires of sovereign nations.

Time zone offsets are identified as -12 UTC through 0 to +12 UTC with the minus values signifying time 'before' or ahead of prime meridian (which is the Western Hemisphere). At the meeting of the -12 and +12 time zones is the International Date Line.

Universal coordinated time conversion chart

Moving west across the International Date Line one moves from the -12 UTC time zone to the +12 UTC time zone. This means you advance the clock 24 hours; in essence you advance one day on the calendar. Moving east across the International Date Line means subtracting 24 hours from the clock thereby reversing one day on the calendar.

The 24-hour clock (Z-time) begins at midnight (00Z) at this prime meridian. 00Z for the United States begins in the evening local time. Z-time does not change with the change for daylight saving time but the local time will change. For example, 00Z in the Central STANDARD Time is at 6:00 p.m. but 00Z occurs at 7:00 p.m. in Central DAYLIGHT SAVING Time.

The following tables show z-times for each time zone in the United States and U.S. Territories.

Universal
Standard Time (UTC offset)
Z-timeGuam
(+10)
Hawaii
(-10)
Alaska
(-9)
Pacific
(-8)
Mountain
(-7)
Central
(-6)
Eastern
(-5)
Atlantic
(-4)
00z10 a.m.2 p.m.*3 p.m.*4 p.m.*5 p.m.*6 p.m.*7 p.m.*8 p.m.*
01z11 a.m.3 p.m.*4 p.m.*5 p.m.*6 p.m.*7 p.m.*8 p.m.*9 p.m.*
02z12 noon4 p.m.*5 p.m.*6 p.m.*7 p.m.*8 p.m.*9 p.m.*10 p.m.*
03z1 p.m.5 p.m.*6 p.m.*7 p.m.*8 p.m.*9 p.m.*10 p.m.*11 p.m.*
04z2 p.m.6 p.m.*7 p.m.*8 p.m.*9 p.m.*10 p.m.*11 p.m.*12 mid
05z3 p.m.7 p.m.*8 p.m.*9 p.m.*10 p.m.*11 p.m.*12 mid1 a.m.
06z4 p.m.8 p.m.*9 p.m.*10 p.m.*11 p.m.*12 mid1 a.m.2 a.m.
07z5 p.m.9 p.m.*10 p.m.*11 p.m.*12 mid1 a.m.2 a.m.3 a.m.
08z6 p.m.10 p.m.*11 p.m.*12 mid1 a.m.2 a.m.3 a.m.4 a.m.
09z7 p.m.11 p.m.*12 mid1 a.m.2 a.m.3 a.m.4 a.m.5 a.m.
10z8 p.m.12 mid1 a.m.2 a.m.3 a.m.4 a.m.5 a.m.6 a.m.
11z9 p.m.1 a.m.2 a.m.3 a.m.4 a.m.5 a.m.6 a.m.7 a.m.
12z10 p.m.2 a.m.3 a.m.4 a.m.5 a.m.6 a.m.7 a.m.8 a.m.
13z11 p.m.3 a.m.4 a.m.5 a.m.6 a.m.7 a.m.8 a.m.9 a.m.
14z12 mid4 a.m.5 a.m.6 a.m.7 a.m.8 a.m.9 a.m.10 a.m.
15z1 a.m.#5 a.m.6 a.m.7 a.m.8 a.m.9 a.m.10 a.m.11 a.m.
16z2 a.m.#6 a.m.7 a.m.8 a.m.9 a.m.10 a.m.11 a.m.12 noon
17z3 a.m.#7 a.m.8 a.m.9 a.m.10 a.m.11 a.m.12 noon1 p.m.
18z4 a.m.#8 a.m.9 a.m.10 a.m.11 a.m.12 noon1 p.m.2 p.m.
19z5 a.m.#9 a.m.10 a.m.11 a.m.12 noon1 p.m.2 p.m.3 p.m.
20z6 a.m.#10 a.m.11 a.m.12 noon1 p.m.2 p.m.3 p.m.4 p.m.
21z7 a.m.#11 a.m.12 noon1 p.m.2 p.m.3 p.m.4 p.m.5 p.m.
22z8 a.m.#12 noon1 p.m.2 p.m.3 p.m.4 p.m.5 p.m.6 p.m.
23z9 a.m.#1 p.m.2 p.m.3 p.m.4 p.m.5 p.m.6 p.m.7 p.m.
Note: *The previous day #The next day
Daylight Saving Time (UTC offset)
Z-timeGuam
(+10)
Hawaii
(-10)
Alaska
(-8)
Pacific
(-7)
Mountain
(-6)
Central
(-5)
Eastern
(-4)
Atlantic
(-3)
00z10 a.m.2 p.m.*4 p.m.*5 p.m.*6 p.m.*7 p.m.*8 p.m.*9 p.m.*
01z11 a.m.3 p.m.*5 p.m.*6 p.m.*7 p.m.*8 p.m.*9 p.m.*10 p.m.*
02z12 noon4 p.m.*6 p.m.*7 p.m.*8 p.m.*9 p.m.*10 p.m.*11 p.m.*
03z1 p.m.5 p.m.*7 p.m.*8 p.m.*9 p.m.*10 p.m.*11 p.m.*12 mid
04z2 p.m.6 p.m.*8 p.m.*9 p.m.*10 p.m.*11 p.m.*12 mid1 a.m.
05z3 p.m.7 p.m.*9 p.m.*10 p.m.*11 p.m.*12 mid1 a.m.2 a.m.
06z4 p.m.8 p.m.*10 p.m.*11 p.m.*12 mid1 a.m.2 a.m.3 a.m.
07z5 p.m.9 p.m.*11 p.m.*12 mid1 a.m.2 a.m.3 a.m.4 a.m.
08z6 p.m.10 p.m.*12 mid1 a.m.2 a.m.3 a.m.4 a.m.5 a.m.
09z7 p.m.11 p.m.*1 a.m.2 a.m.3 a.m.4 a.m.5 a.m.6 a.m.
10z8 p.m.12 mid2 a.m.3 a.m.4 a.m.5 a.m.6 a.m.7 a.m.
11z9 p.m.2 a.m.3 a.m.4 a.m.5 a.m.6 a.m.7 a.m.8 a.m.
12z10 p.m.2 a.m.4 a.m.5 a.m.6 a.m.7 a.m.8 a.m.9 a.m.
13z11 p.m.3 a.m.5 a.m.6 a.m.7 a.m.8 a.m.9 a.m.10 a.m.
14z12 mid4 a.m.6 a.m.7 a.m.8 a.m.9 a.m.10 a.m.11 a.m.
15z1 a.m.#5 a.m.7 a.m.8 a.m.9 a.m.10 a.m.11 a.m.12 noon
16z2 a.m.#6 a.m.8 a.m.9 a.m.10 a.m.11 a.m.12 noon1 p.m.
17z3 a.m.#7 a.m.9 a.m.10 a.m.11 a.m.12 noon1 p.m.2 p.m.
18z4 a.m.#8 a.m.10 a.m.11 a.m.12 noon1 p.m.2 p.m.3 p.m.
19z5 a.m.#9 a.m.11 a.m.12 noon1 p.m.2 p.m.3 p.m.4 p.m.
20z6 a.m.#10 a.m.12 noon1 p.m.2 p.m.3 p.m.4 p.m.5 p.m.
21z7 a.m.#11 a.m.1 p.m.2 p.m.3 p.m.4 p.m.5 p.m.6 p.m.
22z8 a.m.#12 noon2 p.m.3 p.m.4 p.m.5 p.m.6 p.m.7 p.m.
23z9 a.m.#1 p.m.3 p.m.4 p.m.5 p.m.6 p.m.7 p.m.8 p.m.
Note: *The previous day #The next day

Regardless which National Weather Service weather map, radar, or satellite picture you view, be sure to first check the time of the image as it will be reported in 24-hour 'Z' time.


What is UTC or GMT Time?

Weather observations around the world (including surface, radar, and other observations) are always taken with respect to a standard time. By convention, the world's weather communities use a twenty four hour clock, similar to 'military' time based on the 0° longitude meridian, also known as the Greenwich meridian.

Prior to 1972, this time was called Greenwich Mean Time (GMT) but is now referred to as Coordinated Universal Time orUniversal Time Coordinated (UTC). It is a coordinated time scale, maintained by the Bureau International des Poids etMesures (BIPM). It is also known as 'Z time' or 'Zulu Time'.

To obtain your local time here in the United States, you need to subtract a certain number of hours from UTC dependingon how many time zones you are away from Greenwich (England). The table below shows the standard difference from UTC time to local time.

The switch to daylight saving time does not affect UTC. It refers to time on the zero or Greenwich meridian, which is notadjusted to reflect changes either to or from Daylight Saving Time.

However, you need to know what happens during daylight saving time in the United States. In short, the local time is advanced one hour during daylight saving time. As an example, the Eastern Time zone difference from UTC is -4 hours during daylight saving time rather than -5 hours as it is during standard time.

Coordinated Universal Time To Mst

Standard TimeDaylight Saving
UTCGuamHIAKPSTMSTCSTESTASTPDTMDTCDTEDT
Diff+10-10-9-8-7-6-5-4-7-6-5-4
0010a2p*3p*4p*5p*6p*7p*8p*5p*6p*7p*8p*
0111a3p*4p*5p*6p*7P*8p*9p*6p*7p*8p*9p*
0212N4p*5p*6p*7p*8p*9p*10p*7p*8p*9p*10p*
031p5p*6p*7p*8p*9p*10p*11p*8p*9p*10*11p*
042p6p*7p*8p*9p*10p*11p*12M9p*10p*11p*12M
053p7p*8p*9p*10p*11p*12M1a10p*11p*12M1a
064p8p*9p*10p*11p*12M1a2a11p*12M1a2a
075p9p*10p*11p*12M1a2a3a12M1a2a3a
086p10p*11p*12M1a2a3a4a1a2a3a4a
097p11p*12M1a2a3a4a5a2a3a4a5a
108p12M1a2a3a4a5a6a3a4a5a6a
119p1a2a3a4a5a6a7a4a5a6a7a
1210p2a3a4a5a6a7a8a5a6a7a8a
1311p3a4a5a6a7a8a9a6a7a8a9a
1412M%4a5a6a7a8a9a10a7a8a9a10
151a%5a6a7a8a9a10a11a8a9a10a11a
162a%6a7a8a9a10a11a12N9a10a11a12N
173a%7a8a9a10a11a12N1p10a11a12N1p
184a%8a9a10a11a12N1p2p11a12N1p2p
195a%9a10a11a12N1p2p3p12N1p2p3p
206a%10a11a12N1p2p3p4p1p2p3p4p
217a%11a12N1p2p3p4p5p2p3p4p5p
228a%12N1p2p3p4p5p6p3p4p5p6p
239a%1p2p3p4p5p6p7p4p5p6p7p
AST - Atlantic, AK - Alaska time, HI - Hawaii time, *The previous day, %The next day

Note: Credit given to NWS Southern Region Headquarters for the information above.


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Coordinated Universal Time To Ist

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