Daylight is increasing by a little more than three minutes each day. Likewise, the angle of the sun in the sky at solar noon is increasing every day. These two things, working together, are increasing the amount of solar radiation coming in from the sun every day. Yet, winter's grip on the region remains firm.
Part of the problem is weather, which changes continuously as weather systems move around, diverting warm air that way and cold air this way. These weather systems move around, aided by steering currents, which sometimes get stuck delivering the same sort of weather to the same location for weeks on end. A certain polar vortex disruption comes to mind.
There are other things at work that can delay warmer weather. Snow reflects a lot of the increased sunlight we are getting. Globally, the heat capacity of water causes a lag in the heating of the oceans.
Spring requires patience. This year more than usual.