Hosea 13:15

‘Though he be fruitful among his brothers, an east wind will come,

The breath of YHWH coming up from the wilderness,

And his spring will become dry, and his fountain will be dried up,

He will make ruination of the treasure of all goodly vessels.'

And just as He had earlier declared that they would simply be blown away by Him into nothingness, now He declares that they will face the burning heat of His anger. Ephraim might at present appear to be fruitful to his brother conspirators among the nations (Egypt, Philistia, etc), but that fruitfulness would be dried up by the scorching east wind, coming from the desert like the breath of YHWH, and his water sources would become dry (compare Leviticus 26:20), and all his goodly treasures, safely stored in the treasure house in goodly vessels, would be ruined.