A "spring day" refers to a day during the season of spring, which is one of the four seasons in a year. Spring typically occurs after winter and before summer, and it is characterized by warmer temperatures, longer days, and blooming flowers and plants. A typical spring day would have pleasant weather with mild sunshine, gentle breeze, and clear blue skies. It's also the time when nature comes back to life after a long winter slumber, making it an ideal season for outdoor activities such as hiking or picnics in parks.