March 6 (Wed)
Keichitsu (啓蟄) is the 3rd of the 24 solar terms (節気) in the East Asian Calendars.
The ground warms up, so hibernating insects come out around this time.
The first thunder after the first day of spring (February 4th) by the old calendar is called “the thunder wakes insects out”. It could be that the thunder wakes insects up with a big bang!
By the way, if you want to put your hina dolls away, this day is a good day for it.