El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle.
El Niño and La Niña are Spanish terms. El Niño means "The Little Boy" and La Niña means "The Little Girl".
The first time that El Niño was originally recognized was back in the 1600s by fishermen off the coast of South America. The phenomenon is unusually warm water in the Pacific Ocean.
This usually occurs around December.
When there is an El Niño it typically brings warmer-than-average temperatures over western and central Canada in the winter months. El Nino does not significantly impact Eastern Canada.
La Niña episodes are the opposite of El Niño. It is a period of below-average sea surface temperatures across the east-central Equatorial Pacific. Global climate La Niña impacts tend to be opposite those of El Niño impacts.
During a La Niña year, above-average precipitation typically occurs in British Columbia, colder-than-normal temperatures in the Prairies and above-average precipitation in Ontario and Quebec.