Breakdown of Ef veðrið helst gott, gistum við þar aftur í næsta mánuði.
Questions & Answers about Ef veðrið helst gott, gistum við þar aftur í næsta mánuði.
Ef means if and introduces a conditional clause.
So Ef veðrið helst gott is the if-clause, and the rest of the sentence is the main clause.
Helst is the present-tense form of haldast, which means stay, remain, or keep being.
So veðrið helst gott means the weather stays good or remains good.
This is slightly different from a verb meaning become. It suggests the weather is already good and continues that way.