The first day of spring can be defined in two ways:

• Astronomical spring starts with the vernal (spring) equinox, when day and night are approximately equal in length. In 2025, this occurs on March 20. So, astronomically, the first day of spring 2025 is Thursday, March 20, 2025.

• Meteorological spring is defined by calendar months for ease of weather statistics and always starts on March 1 and lasts through May 31. Thus, by this definition, the first day of spring is March 1 every year, including 2025.

In summary, the first day of spring 2025 is either March 1 (meteorological) or March 20 (astronomical/vernal equinox), with the equinox being the more commonly recognized official start of spring.