NO aircraft is certified to fly in severe icing conditions.
Having flown the Dash 8 100/300 and Q400 for a couple of thousand hours:
Parts of the Q400 windshield become coverd with ice some times when cruising at very cold temperatures at cruising levels.
BUT when your (heated!) windshield gets frozen up so close to ground (at temperatures around freezing level = rather warm) that would alert me a lot.
I would consider this severe Icing conditions beyond the certified limits.
Interesting to know, that Bombardier considered to modify the Q400 to be equipped with bleed air anti/deicing and getting rid of boots at all.....