If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Strahan: The hottest months are usually January and February, with an average temperature of 14°C, while the coldest months are August and July, with an average of 9°C. The rainiest months in Strahan are July, August, May and September, with each month seeing an average of 254 mm of rainfall.