After setting a record for a single-week period in mid-November, El Niño has continued to produce record warm temperatures in the Pacific Ocean. This climate pattern, characterized by an abnormal warming of the equatorial Pacific Ocean, has already contributed to a large number of weather effects around the planet, including increased hurricane activity in the Pacific Ocean and heat across much of the United States.

Of the metrics used to gauge the strength of El Niño, the most straightforward is to look at temperatures between 90 degrees west and 160 degrees east longitude, and 5 degrees north and 5 degrees south of the equator, known as the Niño 3.4 region. Back on November 16, the National Oceanic and Atmospheric Administration reported that this area of the Pacific had a weekly average temperature that was 3.0 degrees Celsius above normal, a record high, topping the 2.8 degrees Celsius anomaly recorded during the week of November 26, 1997, the last really strong El Niño.

During the last two weeks, the temperature in this key region of the Pacific has stayed at or slightly above 3.0 degrees Celsius, NOAA says. The agency's Climate Prediction Center predicts that El Niño will likely peak during the Northern Hemisphere winter 2015-16 and will transition to neutral conditions during the late spring or early summer 2016. Forecast models predict a peak later this month.

Much of the United States has seen very warm conditions as a result of El Niño. Meteorological fall, which runs from September through November, was the warmest on record for National Weather Service stations in Los Angeles, San Diego, Salt Lake City, El Paso, and New York City. Most of the United States should see continued warmer-than-normal conditions through most of December.

El Niño's effects were also felt in the tropics. Overall, the Atlantic basin—which includes the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico—saw a quiet season. Although there were 11 named storms, as measured by their total duration and intensity, the season's activity was well below normal. This is to be expected as El Niño increases wind shear over the Atlantic tropics.

Meanwhile, in the Pacific Ocean, a number of records fell. According to NOAA, this is the first year since reliable record keeping began in 1971 that the eastern Pacific saw nine major hurricanes. Hurricane Patricia became the strongest hurricane recorded in the Western Hemisphere in terms of both maximum winds, at 320kph, and lowest air pressure, at 879 millibars. Hurricane Sandra, which formed in November, was the strongest hurricane in the eastern Pacific so late in the year, with a maximum sustained wind speed of 235kph.

The central Pacific, too, saw its largest number of storms since the satellite record began in 1971, including eight hurricanes. Three major hurricanes—Ignacio, Kilo, and Jimena—spun at the same time east of the International Dateline, the first time that has ever been recorded.