The worst drought in five years is creeping across the Caribbean. From Puerto Rico to Cuba to St Lucia, crops are withering, reservoirs are drying up and cattle are dying while forecasters worry that the situation could only grow worse in the coming months.

Thanks to El Niño, a warming of the tropical Pacific that affects global weather, forecasters expect the hurricane season that began in June to be quieter than normal, with a shorter period of rains. That means less water to help refill Puerto Rico’s thirsty Carraizo and La Plata reservoirs as well as the La Plata river in the central island community of Naranjito. A tropical disturbance that hit the US territory on Monday did not fill up those reservoirs as officials had anticipated.

Puerto Rico is among the Caribbean islands worst hit by the water shortage, with more than 1.5 million people affected by the drought so far, according to the US National Drought Mitigation Center.

Tens of thousands of people receive water only every third day under strict rationing recently imposed by the island government. Puerto Rico last week also activated national guard troops to help distribute water and approved a resolution to impose fines on people and businesses for improper water use.

The Caribbean’s last severe drought was in 2010. The current one could grow worse if the hurricane season ending in November produces scant rainfall and the region enters the dry season with parched reservoirs, said Cedric Van Meerbeeck, a climatologist with the Caribbean Institute for Meteorology and Hydrology.

“We might have serious water shortages … for irrigation of crops, firefighting, domestic consumption or consumption by the hotel sector,” he said.

The Caribbean isn’t the only area in the western hemisphere dealing with extreme water shortages. Brazil has been struggling with its own severe drought that has drained reservoirs serving the metropolis of São Paulo.

In the Caribbean, the farm sector has lost more than $1m in crops as well as tens of thousands of dollars in livestock, said Norman Gibson, scientific officer at the Trinidad-based Caribbean Agricultural Research and Development Institute.

On St Lucia, which has been especially hard hit, farmers say crops including coconuts, cashews and oranges are withering.

“The outlook is very, very bad,” said Anthony Herman, who oversees a local farm cooperative. “The trees are dying, the plants are dying … It’s stripping the very life of rivers.”

Officials in Cuba say 75% of the island is enduring a drought that has killed cattle and destroyed thousands of hectares (acres) of crops including plantains, citrus, rice and beans. Recent heavy rains in some areas have alleviated the problem some, but all 200 government-run reservoirs are far below capacity.

In the nearby Dominican Republic, water shortages have been reported in hundreds of communities, said Martin Melendez, a civil engineer and hydrology expert who has worked as a government consultant. “We were 30 days away from the entire water system collapsing,” he said.

The tourism sector has also been affected.

Most large hotels in Puerto Rico have big water tanks and some recycle wastewater to irrigate green areas, but many have curtailed water use, said Frank Comito, CEO of the Florida-based Caribbean Hotel & Tourism Association.

Other hotels have cut back on sprinkler time by up to 50%, said Carlos Martínez of Puerto Rico’s Association of Hotels. “Everybody here is worried,” he said. “They are selling water tanks like hot cakes … and begging God for rain.”

Guests at Puerto Rico’s El Canario by the Lagoon hotel get a note with their room keys asking them to keep their showers short amid the water shortage. “We need your cooperation to avoid waste,” says the message distributed at the front desk of the hotel in the popular Condado district.

At the Casa del Vega guesthouse in St Lucia, tourists sometimes find the water in their rooms turned off for the day, preventing them from taking a shower. “Even though we have a drought guests are not sympathetic to that,” hotel manager Merlyn Compton said.