The start of Spring in the Northern Hemisphere coincides with the vernal equinox.

There are only two times of the year when the Earth’s axis is tilted neither toward nor away from the sun, resulting in a “nearly” equal amount of daylight and darkness at all latitudes. These events are referred to as Equinoxes (the vernal equinox is the beginning of spring, while the autumnal equinox is the beginning of fall). The word equinox is derived from two Latin words – aequus (equal) and nox (night). At the equator, the sun is directly overhead at noon on these two equinoxes. The “nearly” equal hours of day and night is due to refraction of sunlight or a bending of the light’s rays that causes the sun to appear above the horizon when the actual position of the sun is below the horizon. Additionally, the days become a little longer at the higher latitudes (those at a distance from the equator) because it takes the sun longer to rise and set. (Source: weather.gov)

Spring cleaning is/was a real practice for many cultures, especially for those in climates with a cold winter.

Some researchers trace the origin of spring cleaning to the Iranian Nowruz, the Persian new year, which falls on the first day of spring. Iranians continue the practice of khaneh tekani (Persian: خانه‌تکانی; literally “shaking the house”) just before the Persian new year. Everything in the house is thoroughly cleaned, from the drapes to the furniture. Another possibility has been suggested that the origins of spring cleaning date back to the ancient Jewish practice of thoroughly cleansing the home in anticipation of the springtime festival of Passover (Pesach). (Source: wikipedia.com)

“Spring fever” is a condition that has been documented by poets for centuries.

“Spring fever is not a definitive diagnostic category,” says Michael Terman, director of the Center for Light Treatment and Biological Rhythms at Columbia University Medical Center. “But I would say it begins as a rapid and yet unpredictable fluctuating mood and energy state that contrasts with the relative low [of the] winter months that precede it.” There is plenty of evidence to point in the direction of spring fever being a real condition: there are distinct patterns of winter depression (aka seasonal affective disorder – SAD) lifting in the spring; the human body’s production of luteinizing hormone, which produces testosterone in men and triggers ovulation in women, peaks to 20 percent above average during June—technically the tail end of spring; and research shows that temperatures in the spring are closest to optimal for fostering a good mood while spending time outside. While the evidence for spring fever remains largely anecdotal, spring fever edges away from science fiction, even if it is not quite science fact. (Source: scientificamerican.com)