In the northern hemisphere the Vernal Equinox occurs this year on March 20.
http://www.timeanddate.com/calendar/spring-equinox.html
The vernal equinox is the astronomical beginning of the season of spring but there have been signs of spring around us for weeks.
I found some interesting ideas about the spring season that you may enjoy considering: http://en.wikipedia.org/wiki/Spring_(season). The most obvious one is that spring in the southern hemisphere is at the time of our autumn. But the spring that we celebrate in the United States is not universally tied to the vernal equinox. Remember Ground Hog Day or Candlemas? Well if the weather is mild then we consider that to be the beginning of spring. According to calendars more closely tied to the cycles of the moon such as the Chinese calendar http://en.wikipedia.org/wiki/Chinese_calendar spring consists of the end of winter, early February to the late spring in May with the vernal equinox being mid-spring. The Celtic traditions also begin their celebration in early February with St Brigit’s day or Imbolc, which is half way between the winter solstice and the vernal equinox in the Northern Hemisphere. http://en.wikipedia.org/wiki/Imbolc.
Many religious traditions are tied to the calendar in the Northern Hemisphere. Did you ever stop to think about how that might work if you lived in the southern hemisphere such as in Australia? Here’s some food for thought. http://www.quora.com/How-are-seasonal-holidays-such-as-Christmas-and-Easter-perceived-and-celebrated-differently-in-the-Southern-Hemisphere
Ecologists interpret spring based on the phenomena they observe in the natural environment. What plants are budding, blooming? What is the condition of the soil? What is the behavior of the birds: are they nesting, migrating, is their plumage changing color? What insects are emerging and what is the activity of mammals, reptiles and amphibians? These phenomena are tied to weather but also to the length of daylight.
So, as the vernal equinox brings on spring in full force go out and begin to observe what is happening in the natural world around you. Maybe you could pick one plant in your yard or neighborhood and see what happens to it over the next week and month. I hope you enjoy!