State news agency KCNA said main rice-growing provinces had been badly affected and more than 30% of rice paddies were “parching up”.
Hundreds of thousands of North Koreans are believed to have died during a widespread famine in the 1990s.
This drought is unlikely to be as deadly because of recent agricultural reforms, correspondents say.
The United Nations World Food Programme says North Korea regularly faces significant food shortages and currently about a third of children in the country are malnourished.
KCNA said granaries in the provinces of South Hwanghae, North Hwanghae, South Phyongan and South Hamgyong were “badly affected”.
North Korea’s troubles
- Average per capita income of $1,000-$2,000 (£640-£1,280) per year, compared to more than $20,000 in South Korea.
- Suffered famine from 1995 to 1997 after series of droughts and floods
- Almost a third of children under five are stunted by malnutrition, says UN
- About 20% of pregnant and breast-feeding women also malnourished
- More than two million people receiving help from UN World Food Programme
It added that it was planting other crops in rice paddy fields of drought-stricken areas to “reduce damage”.
Last year the country saw its lowest rainfall in 30 years.
The BBC’s Stephen Evans in Seoul says that since the famine in the 1990s, North Korea has allowed more privately organised farming and output has risen.
For this reason, food shortages caused by the current drought are unlikely to be on the same scale, he says.
Other countries, including South Korea, regularly send aid to the North. In April the UN called for $111m (£71m) to fund humanitarian activities in food, nutrition, agriculture and sanitation.
worst drought in a century