Planning for the weather is a good way to make your trip to Rangárþing ytra relaxing and enjoyable, especially when you're splurging. The hottest months are usually July and August, with an average temperature of 8°C, while the coldest months are December and January, with an average of -3°C. The rainiest months in Rangárþing ytra are January, September, February and March, with each month seeing an average of 183 mm of rainfall.