If you're looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Sealevel: The hottest months are usually July and August, with an average temperature of 26°C, while the coldest months are January and February, with an average of 12°C. The rainiest months in Sealevel are August, September, July and June, with each month seeing an average of 180 mm of rainfall.