Changeable, variable (Oxford Dictionary).

subject to change; "a changeable climate"; "the weather is uncertain"; "unsettled weather with rain and hail and sunshine coming one right after the other"

A period of variable and uncertain weather.

A term used to describe when earth geomagnetic fields are unsettled.

With regard to geomagnetic activity, a descriptive word defining conditions between quiet and active, specifically meaning that the A index is between 8 and 15.

To present participles which come from intransitive verbs, or are themselves employed as adjectives, to mark the absence of the activity, disposition, or condition implied by the participle;

not settled or established; "an unsettled lifestyle"

not yet settled; "unsettled territory"

still in doubt; "an unsettled issue"; "an unsettled state of mind"

lacking order or stability; "these unsettled times"