Do spend some time with one of those weather sites - average high/low, hours of daylight/sunshine, average rainfall, etc. for your dates.
I'm from MN. I once went to Italy in February. MN Feb is something like an average high/low of 22/7. I'd looked at the average Italy Feb high and seen 65 for my intended area. It seemed so warm compared to the blizzard and inches of ice outside. Packed shorts and t's. Indeed there was a high of 65 there, but I about froze. Finally realized that 65 is how high I heat my house in the winter, and I dress in wool socks, long pants, long-sleeved tops, and thick sweaters.
For March in Europe, think south, think near oceans/seas, think near warm ocean currents, think lower elevations. Or think dressing warmly, museums and other indoor amazing things for other areas.