August in Portlaoise is the rainiest month of the year. In August, the weather in Portlaoise is typically warm. Average daily high temperature in August is about 16 degrees above zero. On average, Portlaoise has 28 rainy, 2 sunny, and 1 cloudy day in August. The rains are usually moderate. August as well as January, February, March, and April is considered the most uncomfortable time to visit Portlaoise.