[Autumn]

I had these in mind for an idea once, I think I'll jot them down in this thread (Minus some of the rain one given we're getting Rainstorm now)

Rain - Commences if it is raining in the area that you request a fight in.
-Forest Dungeons now have a chance of any floor generating with rain.
-Gumshoes prevent the effects of Muddy

Sandstorm - Commences if there is a sandstorm ongoing in the area you request a fight in.
-All units suffer -25 Hit during a sandstorm. (If the sandstorm is neutral, all units are affected.)
-"Sunglasses" accessory prevents this effect from happening.
-Desert dungeons now have a chance of any floor generating with a sandstorm.

Snowing - Commences if it is snowing in the area you request a fight in.
-All units gain the chilled debuff, which reduces movement by 2 and ice resistance by 10%.
-"Scarf" accessory prevents this effect from happening
-Ice Caverns now have a chance of any floor generating with snow.

Hurricane -
-"Sylph Cloak" accessory prevents the effects of hurricane from happening.

I would assume that "Umbrella" could be used for Rainstorm as well.