If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Ferndale: The hottest months are usually August and July, with an average temperature of 16°C, while the coldest months are February and December, with an average of 4°C. The rainiest months in Ferndale are November, January, December and March, with each month seeing an average of 243 mm of rainfall.