...and more
In terms of precipitation, rainfall in Cardiff ranges from 2.0 - 3.5 inches per month. January is typically the wettest month, when rainfall can reach 3.5 in. April is typically the driest time to visit Cardiff when rainfall is around 2.0 in.
If weather is an important factor for your trip to Cardiff, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 64.4 F. Travelers looking to avoid the cold should look outside of December, when temperatures are typically at their lowest (around 39.2 F).