More than 2 million people could face starvation by the end of the summer, unless there are urgent efforts to respond to the drought in Somalia.

Mark Lowcock, the UN’s humanitarian chief, said the country is facing one of the driest rainy seasons in more than three decades, and a “rapidly deteriorating humanitarian situation”.

By September, 2.2 million people will face hunger so severe that it threatens their lives or livelihoods. A further 3.2 million people – around one-fifth of Somalia’s population – will be uncertain of their next meal.

“If there isn’t a rapid response, there’s going to be a big problem,” said Lowcock.

Last week, the UN warned that, rather than ramping up work, agencies had been forced to cut back in some areas because the humanitarian appeal for Somalia was so poorly funded.

The crisis comes as communities struggle to recover from a two-year drought that ended in 2017.

“We were caught by surprise at just how quickly this drought has returned,” said Nasra Ismail, director of the Somalia NGO Consortium. “The time for people to recover has been halved and has been continuing to decrease every single season,” she said. “Ultimately, it’s climate crisis.”

The April to June period, initially forecast as an average rainy season, is now thought to be one of the driest on record in more than 35 years.

The failed rainy season was partly caused by cyclones in the southern Indian Ocean, including Cyclone Idai in March, which stopped rains from moving north. This has come on top of abnormally hot and dry conditions between January and March, and a poor “deyr” season, between October and December last year.

While there has been some rainfall in recent weeks, it is still well below what is needed, leading to the devastation of crops and death of livestock.

Lowcock said agencies faced a severe lack of funding, but that intervening early would avert the worst human suffering and prove more cost-effective. The humanitarian response plan, which sought $1.08bn (£848m) for the year, had received only a fifth of this amount by the end of May. The appeal has since been replaced by a drought response plan, for which $710m is being sought.

The UN has allocated $45m to offer support in Somalia, as well as parts of Ethiopia and Kenya. The majority of the funds, $30m, will go to Somalia.