Indian officials say the affected regions of Saurashtra, Kutch and north Gujarat received just 45% of their average annual rainfall last year, and crops worth 42.5 billion rupees ($988m, or £650m) have been lost.
Experts estimate that Pakistan has a one-third shortfall in irrigation water supplies.
Seasonal rains there are late and officials say some key crops could be devastated if monsoon rains fail to arrive.
Tensions are also running high in India's Jamnagar district, where police shot dead three men when farmers blocked a highway to protest at plans to divert water to a local town.
Gujarat's leaders reckon their drought is the worst in 13 years and that it is affecting 25 million people.
Over 75% of the 900 villages in Rajkot district face an acute shortage of drinking water and nearly half of the villages there are entirely dependent on water supplied by tankers.
The drying up of all water reservoirs in the western Saurashtra region has forced the local authorities to buy water from privately-owned wells.
Aid plea
More emergency relief aid is being sought by Gujarat officials to help stem the growing crisis, specifically food for children and fodder for cattle.
Indian officials say the affected regions of Saurashtra, Kutch and north Gujarat received just 45% of their average annual rainfall last year, and crops worth 42.5 billion rupees ($988m, or £650m) have been lost.
The drought afflicting southern Afghanistan has prompted the United Nations to express concern about the increased risks of dysentery, diarrhoea and related diseases.
Farmers in the capital, Kabul, are also being hit as their only sources of irrigation are water channels cut from the Kabul river.