Much like our natural world has seasons, so does the church year. Instead of marking weather patterns, seasons of the church year mark important events relating to the life, death, and resurrection of our Lord Jesus Christ.
We are currently in the Season of The Holy Trinity, when we celebrate the doctrine of The Holy Trinity or the three Persons of God the Father, the Son, and the Holy Spirit.
Read more about the Season of The Holy Trinity on the LCMS website.