Its because the Earth's axis is tilted. It is all about the tilt of the Earth's axis. Many people believe that the temperature changes because the Earth is closer to the sun in summer and farther from the sun in winter.
why is it hot in the spring?
how did spring get its name?
Before Spring was called Spring, it was called Lent in Old English. Starting in the 14th century, that time of year was called “springing time”—a reference to plants “springing” from the ground. In the 15th century this got shortened to “spring-time,” and then further shortened in the 16th century to just “spring.”