Under the astronomical calendar, the season usually begins around March 20th. Because the season starts nearly three weeks late compared to the meteorological calendar, the "first month" is the remainder of March. This pushes into the slot of the second astronomical month of spring.
The second month of spring depends on the system you’re using: what is the second month of spring
Beginning with the equinox around September 22nd, the second month of the season spans from mid-October to mid-November . Why April and October are the "Heart" of Spring Under the astronomical calendar, the season usually begins