Weather at DC early March?

[3littlepeas]

I know this is question without a "for sure" answer but I just want to hear from all the experts out there before I open the wallet...Am I risking it booking DC with dolphin encounter in late Feb/early March. There are 5 of us, so....I don't mind low 20s (that's in celsius folks) but I don't want 10s....
Thank you!!!