Days of the Week
The order of the weekdays is:
Firesday >> Earthsday >> Watersday >> Windsday >> Iceday >> Lightningday >> Lightsday >> Darksday
The cycle then repeats (Darksday is followed by Firesday).
Time of Day
The effects of certain equipment, for example Ninja Kyahan and Louhi's Mask, are activated depending on the Vana'diel time of day and certain quests can only be completed or advanced during certain times of day. Additionally, certain monster's aggressive behavior changes depending on the time of day and certain monsters are only present at certain times of day. For example, Eruca and Karakul sleep for most of the night and are not aggressive during that time. Undead monsters typically only appear in outdoor field areas in the middle of the night (20:00-4:00). A Vana'diel day is split in half for day and night. A limited number of equipment pieces, like Ninja Kyahan +1, have an effect activated from "dusk to dawn." Dusk to dawn expands the nighttime range by an additional hour on either end.
- Daytime: 6:00 - 18:00
- Nighttime: 18:00 - 6:00
- Dusk to Dawn: 17:00 - 7:00
- For players and monsters alike, weekday can have an impact on elemental damage of all kinds (magic, elemental weapon skills, and skillchains) as well as cure potency. Magical damage associated with the current weekday (e.g. Thunder spells on Lightningday) has approximately a 1/5 chance of being boosted by 10%. Similarly, magical damage descendent to or opposed with the current weekday (e.g. Fire spells on Watersday) may be reduced by 10%.
- Elemental Obis obtained from In the Name of Science can be equipped to guarantee the positive (and negative) effects of the current weekday on associated magical damage.
- Twilight Cape enhances the damage bonus by an additional 5% when it procs.
- Sorcerer's Tonban/+1 enhances the damage bonus by an additional 5% with or without a proc.
- Zodiac Ring enhances the damage bonus by an additional 3% with or without a proc.
- Weekday can activate effects on certain equipment pieces (e.g. Fire Belt or Athos's Gloves).
- Weekday plays a direct role in many magians trials, where certain monsters must be defeated on certain weekdays.