Hiya, we went in March a couple of years ago and it was one of the best times we have had in Malta. We went second to last week in March and it wasn't hot but it was warm but a bit windy. I took a denim jacket and my other half a zip up sweatshirt and sometimes we needed them sometimes we didn't. It was nice enough for me pair cropped trousers and a t shirt, other half jeans and a t shirt. On the thursday and friday it was lovely, some people were actuall in the sea and on Meliieha bay sunbathing (I didn't think it was that warm!) At night it was cool but again denim jacket and sweat top was enough.
It was a fantastic holiday, wonderfull for sightseeing, we usually go in July and August and it's too hot to walk round but it was great in March. We are going on the 30th March this year and I cannot wait.
Have a fab holiday.