Sie hatten schon seit über einem Monat keinen Regen mehr in Afrika.

English Translation

They have had no rain in Africa for more than a month.

Why is it ‘einem’ Monat? I thought that einem would imply dative and that über usually uses accusative? :thinking:

“Über” can take both dative and accusative, depending on whether it is a direction or location.
But in this sentence, the case is dictated by “seit” (you can omit the über), which takes the dative case.