Many of the areas of Vana'diel exhibit weather patterns associated with their regions, from blizzards in the Fauregandi region to sandstorms in the Kuzotz region, with a multitude of patterns in between.
Each of the possible weather patterns are associated with one of the eight elements, with a double icon representing a stronger weather condition than a single icon:
- hot spell / heat wave
- snow / blizzards
- winds / gales
- dust storms / sandstorms
- thunder / thunderstorms
- rain / squalls
- auroras / stellar glare
- gloom / miasma
Other types of "normal" weather are not associated with any of the elements (sunshine, fair, clouds, and fog). Weather for the current day and the next two days can be forecasted by certain Weather Forecast NPCs or by selecting the related option in the Magian Spectacles dialog after using. Weather Forecast NPCs show weather patterns for areas nearby the zone in which the NPC is located while Magian Spectacles will only forecast weather for the area in which the player is located. Outdoor field areas in the same region often exhibit different weather conditions, but dungeon areas typically exhibit the same weather conditions as the field area from which they are entered at any given time. For example, the weather in The Boyahda Tree matches that in The Sanctuary of Zi'Tah.
Just like on Earth, weather in some regions of Vana'diel is strongly subject to seasonality based on the Vana'diel calendar. For example, while it rains fairly frequently in Rolanberry Fields during the early and late months of the year, it almost never rains in the summer months. Similarly, The Sanctuary of Zi'Tah has thunderstorms almost daily during the summer months, but much less frequently in the winter.
The effects of weather are more than just visual:
- For players and monsters alike, weather has a strong impact on elemental damage of all kinds (magic, elemental weapon skills, and skillchains) as well as cure potency. Magical damage associated with the current weather condition (e.g. Thunder spells during a thunderstorm) has approximately a 1/3 chance of being boosted by 10% during single weather and by 25% during double weather. Similarly, magical damage descendent to or opposed with the current weather (e.g. Fire spells during rain) may be reduced by the same percentages.
- Elemental Obis obtained from In the Name of Science can be equipped to guarantee the positive (and negative) effects of the current weather on associated magical damage.
- Helix spells will always be impacted by the positive (and negative) weather bonus.
- Twilight Cape enhances this bonus by an additional 5% (+0.05 to the multiplier).
- Iridescence from Iridal Staff or Chatoyant Staff provides an additional chance at a 10% bonus which can proc separately or together with normal weather bonus, increasing the likelihood of a 10% weather bonus and adding the possibility for a 20% bonus.
- In many areas, Elemental monsters of the current weather type appear when weather effects are active. Additionally, there are several notorious monsters that only spawn in certain weather conditions (e.g. Noble Mold).
- Weather can activate effects on certain equipment pieces (e.g. Summoner's Horn).
- Weather plays a direct role in many magians trials, where certain monsters must be defeated while certain weather conditions are in effect. For these trials, defeating one target while the weather is active will fulfill five objectives towards the trial completion.
- Scholar storm spells are similar to single weather in their effects on boosting (or reducing) magical damage and activating weather effects on equipment; however, they do not fulfill the requirements for Magians weather trials. They can stack with single weather to create double weather for the purposes of boosting magical damage, but they do not provide any further bonus when double weather is already in effect. The weather from a storm spell will always take precedence over the area's weather (e.g. although Dynamis has permanent miasma weather, with Aurorastorm, or any other weather spell except Voidstorm, the dark weather penalty to cures will never occur).