the weather in Sofia sounds very much like New England. The latitude is the same, 42 degrees north.

April is a crazy month with days warm enough for shorts and T-shirts, and other days you need that winter coat!  Back in 1997 there was a blizzard on April Fool's day.  Snow has fallen here as late as April 19, fortunately not more than an inch or so of messy slush, which doesn't last long. It puts a damper on spring, for sure.