These months can bring a wide variety of weather. Within a few days, the temperature can vary between the lower 40's and the lower 90's. Any form of precipitation is possible so expect to bring a wide variety of clothes to change into. The temperatures can range from 20-80 degrees, but usually these variations are not rapid. If you will be here during this time period, bring warm clothing and something to keep you dry.
Snow is always a possibility.
It is not uncommon for the thermometer to dip below 0. Bring lots of warm clothing and prepare to layer. Also drive very carefully because roadways can be slick with ice. 20's are not uncommon in March. It can also get to be around 80 in April.