Hi Darcie! Thanks for stopping by the Disney Parks Moms Panel with your question!
My son's birthday is in early March, and we always plan a visit to Walt Disney World to celebrate. The biggest variable on crowd levels in March is Easter. When it falls in late March or early April, the crowds can be larger near the middle to end of the month. When the holiday is later in April, the biggest crowds hold off until then. This year, Easter falls on April 5, so crowds will really swell that last week of March into the first week of April. Keep in mind, too, as schools begin letting out for spring break throughout the month, the parks will start to get busier.
If you do an internet search for "Disney crowd calendars," you'll find even more detailed information on what crowds are like at any given time. Some are free, some require a paid subscription.
We love visiting in early March, and I think if you can make it during the first half of the month you'll have a great time. I hope this helps you make your plans, Darcie. Wishing you and your family a magical Walt Disney World vacation!
Kathy K.