The awakening of the insects represents spring is here. Spring thunders begin as new life sprouts. The harsh winter nourished the land the insects within the rocks and holes awaken by the spring thunder. Spring is here!
In this solar term, the farmers are busy planting the sprouts. If there is thunder before this solar term, then it means the rain (weather) will be abnormal and may result in natural disasters.
As the saying goes...「未到驚蟄雷先叫，四十九日暗天打」thunder calling before the awakening of insects means continue anger of the weather. (sorry may not be the best translation...)
Try practicing meditation on this day! It is when the energy between the sky and earth is strong. It will be easier to enter meditation and receive energy of the universe.