The US space agency Nasa has warned that the effects of the current El Nino weather phenomenon could be as bad as those of 1998, the strongest on record.
That El Nino played havoc with world weather systems and was blamed for several extreme weather events.
The current El Nino has been linked to several floods and unusually warm conditions in the northern hemisphere.
The phenomenon sees warm waters of the central Pacific expand eastwards towards North and South America.
El Nino, which occurs every two to seven years, usually peaks late in the calendar year, although the effects can persist well into the following spring and last up to 12 months.
Nasa says the current El Nino “shows no signs of waning”, based on the latest satellite image of the Pacific Ocean.
It bears “a striking resemblance” to one from December 1997, the agency says, “the signature of a big and powerful El Nino”.
This year’s El Nino has been linked to the worst floods seen in 50 years in Paraguay, Argentina, Uruguay and Brazil.
The floods there have forced more than 150,000 people from their homes.
More than 100,000 of those have been in the Paraguayan capital Asuncion alone.
In the US, 13 people have died in the US state of Missouri as a result of flooded rivers after tornadoes and storms hit the region.
A five-mile (8km) section of the Mississippi River near St Louis was closed to vessels as a result of the “hazardous conditions” that have been caused.
Higher temperatures than the seasonal average have been noted in many parts of Europe and the US.
Average temperatures on Christmas Day in France were the second highest on record, just below those of 1997.
The mild weather has forced farmers to harvest crops such as salad, strawberries and asparagus early, with reports of large amounts of produce going to waste.
Desperation in one French ski resort at the lack of snow led to 100 tons of snow being airlifted in by helicopter.
In Italy, experts say the unusually calm and dry weather has exacerbated pollution over the cities of Milan and Rome.