Weather will likely play an important role when you plan your trip to Deiyannewela, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually March and April, with an average temperature of 24°C, while the coldest months are January and February, with an average of 23°C. The rainiest months in Deiyannewela are November, October, December and April, with each month seeing an average of 355 mm of rainfall.