Question to New-Yorkers...

... or people familiar with the weather in/around the city.

My sister is planning a trip to New-York (twas a gift for her 30th birthday and it's only now, two years later, that she has the opportunity to try and organise it); she has found a great bargain trip for mid-March and was wondering about the weather around this time of the year? Whenever people talk about (gorgeous, dynamic) New-York, they usually also mention the freezing winters and the scalding summers... what about the time in between, then? How it's like around the ides of March? Or by the end of March?

She's been looking on-line but she wanted the opinion of people living there so she asked me to ask you ;)

Thanks in advance for the help!