If you’re hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Portobelo: The hottest months are usually May and September, with an average temperature of 27°C, while the coldest months are January and February, with an average of 26°C. The rainiest months in Portobelo are November, July, August and October, with each month seeing an average of 350 mm of rainfall.