Thailand may not feel full impact of La Niña this year

El Niño wreaked havoc across the world in 2023, creating extreme weather events, drought, wildfires and scorching heatwaves across Southeast and South Asia as well as South America. The weather phenomenon was also felt in North America and South Africa, where it made the cold months warmer.

The National Oceanic and Atmospheric Administration (NOAA) had earlier announced that El Niño would come to an end, and La Niña would arrive in Thailand in August. However, more recent forecasts indicate more of a transition to ENSO-neutral conditions followed by a possible El Niño development. This suggests La Niña is unlikely to have a full effect in Thailand this year.

The El Niño-Southern Oscillation (ENSO) is a dynamic system that can change rapidly, leading to adjustments in forecasts.

What is La Niña?

La Niña refers to a natural oceanographic phenomenon characterised by cooler-than-normal sea surface temperatures in the central and eastern equatorial Pacific. This cooling trend, coupled with stronger southwest winds redistributes warm sea surface waters to the west, resulting in rising sea surface temperatures and sea levels. La Niña occurs every two to three years and typically persists for nine to 12 months or longer.

Normally, the transition from El Niño to La Niña marks a period of neutrality lasting three to five months before the full impact of La Niña is felt. However, if La Niña fails to intensify significantly, temperatures may remain high due to the lingering effects of El Niño.

Despite being considered the “opposite” of El Niño, La Niña’s effects are not really a mirror image of its counterpart.

Pamela Knox, an agricultural climatologist from the University of Georgia Extension, said “it’s a bit more complicated than that”. According to Knox, the impacts of La Niña and El Niño are different in different parts of the world, but the changes help forecasters calculate what the climate will be like in the next few months.

Mickey Glantz, director of the University of Colorado Boulder’s Consortium for Capacity Building, noted that La Niña does not just shift weather patterns but can also intensify rain and heat patterns in some regions.

“La Niña, to me, is ‘extreme normal’,” he said.

Will La Niña affect Thailand?

The Thai Meteorological Department (TMD) had said in March that La Niña will bring more rain to most parts of Thailand. However, apart from bringing temperatures down slightly across the country, La Niña has yet to bring the heavy rain as previously forecast.

The influence of climate change has added a layer of uncertainty to weather forecasts, as rising global temperatures alter the dynamics of El Niño and La Niña cycles.

As scientists grapple with the complexities of climate change and natural variability, the remainder of 2024 serves as a crucial case study for understanding evolving impacts on weather patterns and ecosystems worldwide.