In Aden, the strikes were focused on the rebel-held provincial administration complex in Dar Saad in the north of the city, according to a military official.
He said there were "many dead and wounded" among the Huthi Shiite rebels but was unable to give a precise toll.
The coalition has vowed to keep targeting the Huthis and allied army units loyal to former strongman Ali Abdullah Saleh until they end their insurrection.
Iran is also accused of backing the rebels but Tehran denies providing military support.
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Militia fighters loyal to President Abedrabbo Mansour Hadi have captured 26 Huthis during the fighting in Aden, one of their leaders said.
In the western port city of Hodeida, four civilians were killed and 10 injured when a dairy was hit in the night, said medical sources.
The circumstances of the bombing were unclear, with some witnesses saying the dairy was hit by a coalition air strike and others blaming pro-Saleh forces.
Coalition planes also targeted camps of the Republican Guard, which is loyal to Saleh, around Sanaa and in the central region of Ibb overnight, according to residents.
Several Huthi positions were also targeted in the northern rebel strongholds of Hajjah and Saada.
After entering the capital in September, the Huthis and their allies gradually conquered areas in the centre, west and south before bearing down on Aden last month, prompting Hadi to flee to Saudi Arabia.
The UN said yesterday that at least 93 civilians had been killed and 364 injured since the nearly week-old Saudi-led air campaign began.