TEHRAN –According to the Metrological Organization, the country is forecast to receive less than normal rainfall and experience above-normal heat from the start of the second month of autumn (October 22) to the end of the first month of winter (January 19, 2025).

From the beginning of the current water year (September 22) till October 21, rainfalls were mainly distributed in the southern part of Alborz as well as the northern part of the country. The average rainfall was recorded to be about 38 percent less than normal, ISNA quoted Ahad Vazifeh, an official with Metrological Organization, as saying.

In the same period, the temperature was about 1.5 to 2 degrees Celsius above normal average, he added.

Most of the numerical weather prediction models have forecast below-normal rainfall and above-normal temperature to continue for the next five or six months. They are not due to El Niño and La Niña, but neutral conditions, Vazifeh noted.

The country is predicted to go through weak La Niña conditions during autumn and winter as the water temperature in the tropical Pacific Ocean will not drop significantly.

El Niño and La Niña are opposite extremes of the ENSO, which refers to cyclical environmental conditions that occur across the Equatorial Pacific Ocean.

La Niña is characterized by unusually cold ocean temperatures in the Equatorial Pacific, compared to El Niño, which is characterized by unusually warm ocean temperatures in the Equatorial Pacific.

During El Niño, precipitations are more than normal in fall and winter, while in La Niña, the rains are less and the temperature is higher than normal. 

These changes are due to natural interactions between the ocean and the atmosphere. Sea surface temperature, rainfall, air pressure, and atmospheric and ocean circulation all influence each other.

Under optimal conditions, when La Niña dominates, there is a 60 percent likelihood that the fall season in Iran begins later, and the probability of facing a dry year increases.

MT/MG