If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Palmetto: The hottest months are usually August and July with an average temp of 83°F, while the coldest months are January and February with an average of 66°F. The rainiest months in Palmetto are August, July, September, and June, with each month seeing an average of 8 inches of rainfall.