Because It's Never to Late Be Aware...Umm...
The word "month" has its origins in the word "moon". There are several types of months, but we mostly use the synodic month which is about 29 and a half days long...usually.
March 15 to April 14 is longer than that, but our Gregorian calendar is so messed up and full of exceptions that one more doesn't really matter.
To celebrate this "month", all you need to do is be aware of it.
And now you are.
You're welcome.
You could do something special in this time period to celebrate, but that would be optional. Maybe you'd like to do something related to the number 30, or 31, or 29.5.
Since spring officially will begin in the northern hemisphere during this month, you might consider doing something spring-like.
If you're in the northern hemisphere, how far south do you have to go before people stop being concerned about the four seasons?
How far do you have to go to find people who don't care about the Four Seasons?
Et tu?
The picture? It was scheduled to come out March 15, 2016. Be aware.