Why in News? 

WMO projected that La Niña weather phenomenon may return b/w Sept and Nov 2025. 

• La Niña: Climate phenomenon where surface waters of the central and eastern Pacific Ocean become unusually cold due to stronger trade winds, opposite to El Niño, which has warm sea surface temperatures in the same region. 
• Effects on India’s Monsoon: Boosts southwest monsoon rainfall, benefiting Kharif crops & replenishing rivers, lakes, and groundwater.  
  • Can cause flooding in regions like Assam & Bihar and bring colder-than-normal winters to northern states like J&K and Himachal Pradesh. 

WMO is a UN specialized agency (designated in 1951) for weather, climate, hydrology & related geophysical sciences.  

• Originated from the IMO (founded in 1873) to standardize global weather observations.  
• IMO became WMO in 1950.