HOUSTON — With several record-high temperatures falling this week across Southeast Texas, many are wondering if this will be a repeat of the hot December we saw last year.
The next thing most are wondering is why has it been so warm. And while that question may be complicated to answer, there is a driving force that we can point to that has a large influence on our weather here at home - La Niña.
From the Spanish words for "little girl," La Niña the opposite occurrence of the more well-known El Niño, which is Spanish for "little boy," Simply put, El Niño and La Niña describe water temperature anomalies in the Pacific Ocean off the coast of South America. Above normal temperatures are El Niño, below normal water temperatures are La Niña.
So what do water temperatures 2300 miles away have to do with our weather here in Houston? These water temperatures can affect weather patterns and the location of the jet stream across the United States. The jet stream plays two major roles: Separating warm air from cold air and acting as a path for storm systems.
During a La Niña winter, the jet stream typically stays farther north on average. As a result, the likelihood of seeing warmer temperatures increases across Southeast Texas goes up. Additionally, rain chances trend lower, as storm systems stay to our north.
In fact, of the ten warmest Decembers on record, five happened during La Nina patterns. While that's only 50%, it's important to note that of those ten, La Niña/El Niño records didn't exist for 4 of those seasons (1933, 1922, 1921, and 1948). So of the six years with El Niño and La Niña records, 5 were La Niña seasons.
In addition to the chances for warmer and drier winter weather, the chances for severe storms tend to increase as well. Since it is winter, after all, shots of cold air reaching Southeast Texas are inevitable. With abnormally warm and humid air in place, thanks to the background La Niña pattern, this sets the stage for more volatile storms when the air masses clash.
One such drop in temperatures is expected by the middle of December. In fact, the Climate Prediction Center is forecasting below-normal temperatures across Southeast Texas for the end of the month.
Regardless of whether we are seeing a La Niña or El Niño pattern, it is important to remember that these patterns only point toward the direction temperatures may trend. Cold snaps and winter weather are still possible during La Niña, as we saw during the freeze in 2021.