During June-August 2024, the Pacific Niño sea-surface temperature (SST) index in the eastern Pacific (Niño 1+2) was below-normal. Of the other three Niño indices only the Niño 4, the westernmost index, was above normal while SST conditions in the equatorial central and eastern Pacific were near-zero. Overall, the SST conditions in the equatorial central and eastern Pacific reflected ENSO-neutral conditions. The observed Indian Ocean Dipole (IOD) was near-zero. Both the North Tropical Atlantic (NTA) and South Tropical Atlantic (STA) SST indices were above normal and reflected widespread warmth in the tropical Atlantic. In general, the observed SST anomalies in global oceans were positive.
Above-normal sea-surface temperature anomalies in the Niño 3.4 and Niño 3 regions are predicted to decline during October-December 2024 and are predicted to become weak La Niña conditions. Farther west in the Niño 4 region, the sea-surface temperature anomaly is also predicted to decline and become negative. The strength of the Indian Ocean Dipole (IOD) index is predicted to return to near normal. In the equatorial Atlantic, SSTs are predicted to be above-normal in both the northern (NTA) and the southern (STA) regions during the season with larger positive anomalies for NTA.
Consistent with the anticipated continuation of widespread above-normal sea-surface temperatures in all ocean basins outside of the near-equatorial eastern Pacific Ocean, there is prediction of above-normal temperatures over almost all land areas. Exceptions to this widespread warmth included land areas in the vicinity of the Bering Sea and the Gulf of Alaska, interior western region of the Indian subcontinent, and Southeast Asia. Extensive areas of large increases in probabilities for above-normal temperatures include almost the entire South America, the Caribbean, Central America, southwest and extreme northeast parts of North America, northern regions and between 30ºS - 10ºN over Africa, Arabian Peninsula, northeast parts of the Indian subcontinent extending northward into mountainous regions, the Maritime continent, New Zealand, and the Arctic regions north of 60ºN. Regions with moderate to weaker increase in probabilities for above-normal temperatures include Australia, Europe, between 40º - 60º N over Asia, Greenland, western coastal regions in Southern Africa, and narrow belt along 15ºN in Africa. In coastal areas of southern South America and extending north along the west coast to just north of the equator and into the eastern Pacific, consistent with the predicted emergence of weak La Niña, below-normal temperatures are expected.
Predictions for rainfall are consistent with the expected impacts of La Niña. Enhanced probabilities for near- or below-normal rainfall are predicted over a narrow band along or just north and south of the equator extending eastward from 150ºE to the western coast of South American. Below the equator, there is an additional band of enhanced probabilities for below-normal rainfall starting from 150º W and extending south-eastwards to reach the western coast of South America and crossing into the southern Atlantic. Enhanced probabilities for below-normal rainfall are also predicted over the northeast South America extending into the Atlantic, North America below 45ºN, the Arabian Peninsula extending north-eastward into Central Asia, over the Greater Horn of Africa extending into the Indian Ocean to 90ºE, and parts of eastern Asia. Enhanced probabilities for above-normal rainfall are anticipated over the region centred over the Maritime Continent extending to cover Australia and extending further into the western Pacific to 150ºW. southern regions of Central America and the Caribbean, Arctic regions north of 60ºN, the Indian subcontinent, and regions below 60ºS in the Southern Hemisphere. Other regions of enhanced probabilities for above-normal rainfall include a band across equatorial Africa along 10ºN and off the coast of eastern Asia extending north-eastward Bering Sea and the Gulf of Alaska.
