There were 2,811 armed clashes between government forces and the Houthi rebel alliance between January and June, compared with 3,610 in the whole of 2016.
While the report does not lay blame with any international party for the air raids, the Saudi-led Arab military coalition - allied with President Abd Rabbo Mansour Hadi's exiled government - largely controls Yemen's airspace, while the US has increased drone strikes on suspected al-Qaeda targets in Yemen.
A spokesperson for the coalition did not respond to AFP's requests for comment on Monday.
Since 2015, Yemen has seen a devastating war between the Saudi-backed government and Iran-backed Houthi rebels who took over the capital the previous September.
International rights groups have accused the coalition of bombing civilian areas including public gatherings, markets, hospitals and residential areas across Yemen since the aerial campaign against Houthi rebels began in 2015.
Yemen has also witnessed a deadly cholera outbreak killing more than 2,000 people, which has been described by UN officials as "the largest humanitarian crisis in the world".
The highly contagious disease is treatable, but the collapse of Yemen's infrastructure following more than two years of war has created a "perfect storm for cholera", the World Health Organisation said on Monday, as it revealed more than half a million people had now been infected in the cholera epidemic.
WHO warned that the disease had spread rapidly due to deteriorating hygiene and sanitation conditions, with millions of people cut off from clean water sources across the country.
"Yemen's health workers are operating in impossible conditions," WHO chief Tedros Adhanom Ghebreyesus said in a statement.
"Thousands of people are sick, but there are not enough hospitals, not enough medicines, not enough clean water."
Many of the doctors and nurses needed to rein in the outbreak in Yemen have not been paid for nearly a year.
Agencies contributed to this report.