 Further, humidity did not increase simultaneously in all places; locations farther north (such as the Omo River headwaters) reached maximum humidity (and thus maximum levels of the lakes fed by the rivers) later than locations farther south.This is because maximum humidity occurs when the maximum insolation coincides with the rainy season and this coincidence occurred later in history for the northerly water systems.Nowadays the Suguta Valley is among the driest areas - if not the driest are - close to the equator, with precipitation estimated to be less than most of which falls during spring.