Australia's Bureau of Meteorology announced today that El Nino thresholds have been reached in the tropical Pacific from the first time since March 2010.
El Nino is the name given to unusually warm temperatures in the equatorial Pacific that can cause changes to wind, rainfall and temperature patterns in other parts of the globe. For example, in Canada, an El Nino that lasts through the winter months generally leads to warmer winters from British Columbia to central Quebec and drier conditions inland.
Australia's Bureau of Meteorology isn't the only organization confirming the arrival of El Nino – the U.S. National Oceanic and Atmospheric Administration had announced El Nino's arrival back in March, but said it was weak and unlikely to have major effects on weather patterns. An update in April said El Nino had strengthened slightly over the course of March.
NOAA predicted a 70 per cent chance that El Nino conditions would last through summer and a 60 per cent chance they'd continue through fall. It is set to give another update Thursday.
Based on climate models, meteorologists had been expecting an El Nino for much of last year, but it never arrived.
According to Environment Canada, El Nino events generally appear every two to seven years and last 12 to 18 months, although one El Nino in the early 1990s lasted four years.
Some of the weather patterns linked to El Nino include heavy rainfall in the central Pacific and western North America and reduced rainfall over Indonesia.