El Nino is a natural climate phenomenon in which surface waters of the central and eastern Pacific become unusually warm and cause changes in weather patterns around the world.
"Over 706,100 people have been temporarily affected, with over 113,690 people temporarily displaced from their homes across the country," the office said in its latest update.
Southwest and Jubbaland states were the worst hit, with a total of about 536,608 people affected, OCHA said.
In the Luuq area of southwest Gedo region, some 2,400 people were trapped by floods, the agency said, adding that steps were being taken to rescue them.
Another 14,000 families had been cut off from the main town in Baardhere, OCHA said.
Earlier this year, floods pushed a quarter of a million people from their homes after the Shabelle river in central Somalia broke its banks and submerged the town of Beledweyne.
Aid agencies and scientists have warned climate change is among the key factors accelerating humanitarian emergencies, while those impacted are some of the least responsible for CO2 emissions.
Published 06 November 2023, 12:51 IST