When you're travelling with pets, keeping tabs on the weather can help you make the trip more safe and fun for everyone. The hottest months are usually March and April, with an average temperature of 28°C, while the coldest months are January and February, with an average of 26°C. The rainiest months in Seeduwa - Katunayake are October, May, November and June, with each month seeing an average of 353 mm of rainfall.