With sackcloth - שק sak . The word is in the plural שקים sakkim, sacks, in one of De Rossi's MSS.
In their streets - Publicly. Everywhere there shall be lamentation and grief. Some shall go into the streets, and some on the tops of the houses.
They shall gird themselves with sackcloth - The common token of mourning; and also worn usually in times of humiliation and fasting. It was one of the outward acts by which they expressed deep sorrow (Genesis 37:34; 2 Samuel 3:31; 1 Kings 21:27; 2 Kings 19:1; Job 16:15; the note at Isaiah 3:24).
On the tops of the houses - The roofs of the houses in the East were, and still are, made flat, and were places of resort for prayer, for promenade, etc. The prophet here says, that all the usual places of resort would be filled with weeping and mourning. In the streets, and on the roofs of the houses, they would utter the voice of lamentation.
Shall howl - It is known that, in times of calamity in the East, it is common to raise an unnatural and forced howl, or long-continued shriek. Persons are often hired for this purpose Jeremiah 9:17.