Time passes like this in Eorzea:
00:00 - 01:00 = Ice Hour
01:00 - 02:00 = Water Hour
02:00 - 03:00 = Wind Hour
03:00 - 04:00 = Lightning Hour
04:00 - 05:00 = Fire Hour
05:00 - 06:00 = Earth Hour
06:00 - 07:00 = Ice Hour
07:00 - 08:00 = Water Hour
08:00 - 09:00 = Wind Hour
09:00 - 10:00 = Lightning Hour
10:00 - 11:00 = Fire Hour
11:00 - 12:00 = Earth Hour
12:00 - 13:00 = Ice Hour
13:00 - 14:00 = Water Hour
14:00 - 15:00 = Wind Hour
15:00 - 16:00 = Lightning Hour
16:00 - 17:00 = Fire Hour
17:00 - 18:00 = Earth Hour
18:00 - 19:00 = Ice Hour
19:00 - 20:00 = Water Hour
20:00 - 21:00 = Wind Hour
21:00 - 22:00 = Lightning Hour
22:00 - 23:00 = Fire Hour
23:00 - 24:00 = Earth Hour
More accurately each elemental hour would begin at 00:01 and end on 01:00 but I'm lazy and used 00:00 to 01:00
That completes one day.
Each day is assigned an element. There are thirty two (32) days per game month. The order is always the same in regards the elements except this time you add light and dark after earth and repeat the cycle 4 times yet again.
It should be noted that there are 8 moon phases each lasting a total of four game days, starting with new moon.
New Moon
Day 1 - Ice
Day 2 - Water
Day 3 - Wind
Day 4 - Lightning
Waxing Crescent
Day 5 - Fire
Day 6 - Earth
Day 7 - Astral
Day 8 - Umbral
Waxing Half
Day 9 - Ice
Day 10 - Water
Day 11 - Wind
Day 12 - Lightning
Waxing Gibbous
Day 13 - Fire
Day 14 - Earth
Day 15 - Astral
Day 16 - Umbral
Full Moon
Day 17 - Ice
Day 18 - Water
Day 19 - Wind
Day 20 - Lightning
Waning Gibbous
Day 21 - Fire
Day 22 - Earth
Day 23 - Astral
Day 24 - Umbral
Waning Half
Day 25 - Ice
Day 26 - Water
Day 27 - Wind
Day 28 - Lightning
Waning crescent
Day 29 - Fire
Day 30 - Earth
Day 31 - Astral
Day 32 - Umbral
New Moon
There are 12 months in the year, again the same pattern is seen in regards the order of the six primary elements except this time each element is applied an astral or umbal "shade" which follows suit:
1) Astral Ice Month
2) Umbral Ice Month
3) Astral Water Month
4) Umbral Water Month
5) Astral Wind Month
6) Umbral Wind Month
7) Astral Lightning Month
8) Umbral Lightning Month
9) Astral Fire Month
10) Umbral Fire Month
11) Astral Earth Month
12) Umbral Earth Month
There are also 12 years per game "Epoch" as opposed to 10 in real life. Each year of an epoch is associated with one of the Twelve gods and hence an element.
Earth - Althyk, The Keeper and Nophica, The Matron
Fire - Azeyma, The Warden and Nald'thal, The Traders
Lightning - Byregot, The Builder and Rhalgr, The Destroyer
Ice - Halone, The Fury and Menphina, The Lover
Wind - llymlaen, The Navigator and Oschon, The Wanderer
Water - Nymeia, The Spinner and Thaliak, The Scholar
And im willing to bet money the order of the years is the same elemental pattern seen in the months that is: ice, water, wind, lightning, fire and earth. I don't know who of each element is considered the astral and whom the umbral but that doesn't really matter since the pattern is likely a repition of the months.
At last the epochs make up the eras but to this we are left in the dark. I am certain that a dev posted some information shedding light on the length of each era (i think it's considered roughly 2,000 years) but I haven't dug up hat post.
What's interesting here is that as opposed to the months which begin with astral and end in umbral, the eras begin with umbral and end with astral:
"The Sixth Umbral Era belonged to the waters, as heavy rains fell and the seas rose high, submerging and cleansing all in a great deluge. With time the waters receded, ushering in the present Sixth Astral Era, during which man has again rebuilt his halls and tilled his lands."
What's interesting here is the mention that the 6th umbral era belonged to water, a great flood of sorts. If indeed the 6th umbral and astral eras correspond to the element of water then the order is different than that which we see in the hours, the days and the months of the year.