The translation of this verse can to some extent be modeled after the rendering of verse 28 (see the comments there).

Behold may be translated “Look!” or “You will then see” (Contemporary English Version).

Clouds from the east, and from the north to the south: The clouds move in from the east, but they span the horizon, stretching from north to south, so that as they advance, the whole sky is clouded over.

Their appearance is very threatening, full of wrath and storm: The adjective very threatening is described by the phrase full of wrath and storm. The clouds threaten a violent storm.

An alternative model for this verse is:

• Look! Storm clouds are moving in from the east, covering the whole sky. They are threatening; a violent storm is sure to come.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Esdras. (UBS Helps for Translators). Miami: UBS, 2019. For this and other handbooks for translators see here.