(Bloomberg) -- Weather is rattling the rice market once more, driving prices of the food staple back to the cusp of 15-year highs after a period of calm. 

Supplies were already upended by sweeping export restrictions from top shipper India last year and worries that drier weather from El Niño would curb output in the important growing region of Southeast Asia. Now catastrophic floods in southern Brazil are adding to the jitters. 

Prices of Thai white rice 5% broken — an Asian benchmark — have jumped by $71 since early April to $649 a ton after cooling from their peak in January, when they reached the highest in more than 15 years. The grain is vital for the diets of billions of people in Asia and Africa, and the fresh surge in costs could fan inflationary pressures and raise import bills for buyers.

The severe floods in Brazil contributed to the recent spike in prices, with the state of Rio Grande do Sul — which accounts for 70% of Brazilian rice production — expected to be affected for several weeks to come, according to Charles Hart, a commodities analyst at Fitch Solutions’ BMI unit. 

“The floods have coincided with Brazil’s rice harvest, a portion of which had not been completed,” Hart said. This has “created significant concerns” about domestic production volume and the eventual exportable surplus, he added. 

Read More: Fallout From Brazil’s Historic Floods to Last Into Next Season

President Luiz Inacio Lula da Silva said last week rains will delay rice harvesting in Rio Grande do Sul, which means the country will likely have to import rice and beans. Brazil is the world’s ninth-largest rice exporter, according to data from the US Department of Agriculture. 

Meanwhile, the slowdown in arrivals of new crop supply in Southeast Asia is also bolstering prices, said Peter Clubb, a commodities market analyst at the International Grains Council in London. That’s as harvesting of Thailand’s off-season crop and Vietnam’s main winter-spring crop come to an end, he said. Thailand is the second-biggest exporter, and Vietnam the third largest.

On the demand side, Indonesia is still purchasing sizable volumes, which is helping to support sentiment, Clubb said. The pace of the country’s buying as well as any potential changes to India’s export curbs will influence prices moving forward, he added.

Still, weather conditions remain a major driver. “We’ll need to watch the weather, particularly the wet seasons in Thailand, Vietnam and India over the coming months,” Clubb said. “Key to this will likely be the transition from an El Niño to a La Niña.”

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