Abstract

The wintertime North Atlantic Oscillation is a major mode of variability affecting climate across the Northern Hemisphere, yet its seasonal prediction skill over the North Atlantic remains lower than that over the Pacific. We examine North Atlantic Oscillation predictability through Pacific teleconnections using reanalysis data and multi-model hindcasts from seasonal-to-decadal forecasting systems. Here we show that Central Pacific El Niño events significantly enhance both North Atlantic Oscillation forecast skill and the predictable signal over the North Atlantic. Reanalysis and equatorial Pacific pacemaker experiments reveal that Central Pacific El Niño enhances sea surface temperature variability over the Aleutian region, modulates Atlantic storm-track activity, and strengthens the Pacific–Atlantic teleconnection. Coupled Model Intercomparison Project Phase 6 simulations suggest that more frequent Central Pacific El Niño occurrence under greenhouse warming may favor this teleconnection. These results identify Central Pacific El Niño-driven Pacific–Atlantic teleconnections as an important source of North Atlantic Oscillation predictability and seasonal forecast skill.

Seasonal forecasts for the North Atlantic have long lagged behind those for the Pacific. A new study finds that forecasts of the North Atlantic Oscillation (NAO) become considerably more accurate during winters marked by Central Pacific El Niño.

A team, led by Professor Myong-In Lee of the Department of Civil, Urban, Earth, and Environmental Engineering at UNIST traced the improvement to a stronger climate connection between the North Pacific and North Atlantic. The NAO is a major pattern of atmospheric variability that shapes winter weather across Europe and North America. The study involved researchers from the Korea Institute of Science and Technology (KIST) and the Met Office Hadley Center in the United Kingdom.

Across several seasonal forecasting systems, the correlation between predicted and observed NAO conditions for January and February was 0.48 over the full study period. During Central Pacific El Niño winters, it rose to 0.78, showing a marked increase in forecast skill.

The researchers found that Central Pacific El Niño strengthens a chain of climate interactions linking the two ocean basins. It increases sea surface temperature variability near the Aleutian region of the North Pacific, shifting the position and intensity of the storm track. The resulting changes in atmospheric circulation extend across North America to the North Atlantic, where they influence the NAO. 

Because ocean temperatures change more slowly than the atmosphere, these North Pacific temperature patterns can persist long enough to provide an early signal of atmospheric conditions that develop later over the North Atlantic.

“The North Atlantic has strong internal atmospheric variability, which makes predictable signals difficult for climate models to capture,” said Kiwook Kim, the study's first author. “During Central Pacific El Niño, the stronger connection between the Pacific and Atlantic effectively opens a window of opportunity for more skillful NAO forecasts

The findings also shed light on the signal-to-noise paradox, in which the real atmosphere proves more predictable than climate models suggest. The researchers found that models may underestimate the connection between North Pacific sea surface temperatures and North Atlantic circulation, limiting their ability to capture this predictable signa.

“Where El Niño develops in the Pacific matters for how its influence reaches the North Atlantic,” said Professor Lee. “If climate models can better capture this connection, we may be able to improve seasonal outlooks for the NAO and related winter extremes, including cold spells and heavy snowfall.

The study was published in Communications Earth & Environment , a sister journal to Nature Portfolio journals, on August 27, 2026. The research was supported by the Korea Meteorological Administration and by the Ministry of Science and ICT (MSIT) through the National Research Foundation of Korea (NRF).

Journal Reference

Kiwook Kim, Myong-In Lee, Daehyun Kang, and Adam A. Scaife, “Central Pacific El Niño-driven Pacific–Atlantic teleconnections are an important source of North Atlantic Oscillation predictability,” Commun. Earth Environment. , (2026).