In March, the weather in Haverfordwest is typically cold. Average daily high temperature in March is about 9 degrees above zero. On average, Haverfordwest has 15 rainy, 6 cloudy, 6 partly cloudy, and 4 sunny days in March. The rains are usually moderate. March as well as January, February, April, and May is considered the most uncomfortable time to visit Haverfordwest.