Hello! I’m Josh Warner, a first year from New Jersey intending on majoring in political science and minoring in math. This semester, I’ve been writing quick weekly weather updates for Student Life’s daily email edition. Around the midway point, I also began writing weekend-specific supplements. However, my passion for weather and forecasting is over a decade old. I founded and served as president for three years at my high school’s meteorology club, and hope in the future to foster a similar community here. When I’m not tracking forecasts — or doing homework — you can often find me on the tennis court, table tennis court and chess board.

As a way of wrapping up the semester’s weather reports, I’ve put together a written overview of what to expect from this winter’s weather along with some hand-drawn graphics. There is always uncertainty to weather forecasting, but I nonetheless hope this helps you plan for the months to come.

This winter will be complex and multifaceted. Multiple different and often competing patterns will be at play. The following forecast is relatively general, but should provide a roadmap for the weather to expect this winter. The months covered as winter will be December to March. 

First, let’s look at the key drivers at play. Most important is the El Niño Southern Oscillation. This refers to an area of ocean temperatures in the southern Pacific Ocean. When these temperatures are colder than average, the pattern is known as a La Niña, and when warmer than average, an El Niño. This winter will feature a moderate La Niña. 

Also important, and harder to predict, is the strength of the polar vortex. This refers to temperature anomalies in the stratosphere around the North Pole. Contrary to common belief, a strong polar vortex keeps this cold air ‘locked up’ in the arctic regions, and a weaker polar vortex allows wedges of cold air to dip southward into the United States. There is some indication that the polar vortex will be relatively weak this winter. 

Another important and even harder to predict factor is the North Atlantic Oscillation (NAO). This refers to the temperatures in the northern Atlantic Ocean. A negative NAO will lead to colder patterns, and a positive NAO will lead to warmer ones. Expect this year’s NAO to be variable. 

Put together, a La Niña, weak polar vortex and unstable NAO paint the picture of a variable winter that will feature warm and cold extremes. These players make specific weather patterns conducive to oscillating temperatures and relative dryness. However, the macro-level factors only alter the likelihood of specific weather patterns forming. Micro-level patterns dictate the actual conditions. This makes prediction of exact temperatures and precipitation over the long range more difficult. 

It is important to have a basis of comparison before looking at anomalies. The average highs in St. Louis from December to March are 44, 40, 45, and 56 respectively in degrees Fahrenheit. These months are also the driest of the year, with average precipitation between 2-3 inches each month from December to February, and then 3-4 inches in March (largely due to severe weather). The average seasonal snowfall in St. Louis is 18 inches (1.8 inches when converted to raw precipitation). Due to a location far from any coast or mountain, winter weather can be quite variable and feature sudden shifts. 

Let’s go month by month and take a look at the forecast.

December (figure 1) is shaping up to be much warmer and a touch wetter than average. The confidence in this is high. A jet stream ridge will settle over the central US, leading to a large swath of warm temperatures in America’s heartland. Additionally, storms that ride along the jet stream will generally impact this region, and thus December can see frequent precipitation. The precipitation, however, will come in small, quick batches, and should largely be confined to rain. There should be few travel issues back home for the break. 

Josh Warner’s hand-drawn graphic shows the December forecast. The brown area depicts the typical jet stream, the green area demonstrates seasonably cold and stormy weather, the red area shows warm and dry weather, the orange area shows above average temperatures, the yellow area shows average conditions, the blue illustrates snow chances and the purple shows colder than normal weather.

January (figure 2) is expected to be colder than average with slightly above average precipitation and snow chances. The confidence in this is medium. Despite warm December temperatures, snowpack will be building to our north. As snow creates colder temperatures to the north, the weakening polar vortex will allow surges of this cold air to plunge southward. The contrast between the warm Gulf air and fresh injections of cold air will allow for multiple storms to form, some which will produce snow. Expect the best chances for cold and snow towards the end of the month. Note that the weather will likely be much colder by the return from the break. 

Josh Warner’s hand-drawn graphic for the January forecast.

February (figure 3) is expected to bring roughly average temperatures, precipitation, and snowfall. The confidence in this is medium. The first half of the month likely will be a continuation of the cold and snowy late-January pattern. Warm surges will clash with cold snaps to produce snow chances. However, by the second half of February, expect a warmer pattern to return as the polar vortex strengthens and the La Nina influence takes center stage. Expect the possibility of a few ice storms in late February during this general transition from cold winter air to warmer and drier springlike air. 

Josh Warner’s hand-drawn graphic for the February forecast.

March (figure 4) is expected to be warmer than average with roughly average precipitation. The confidence in this is low. Do not expect late snowfall this winter. However, warm southern and Gulf air can clash with lingering cold air to produce severe weather outbreaks. Severe weather is a major player in St. Louis from March-June, so anticipate bouts of strong thunderstorms with damaging wind and tornado threats. Few “wintry” storm tracks will occur. 

Josh Warner’s hand-drawn graphic for the March forecast.

The prolonged snap of frigid air last February was an anomaly, and likely not to repeat itself. However, being located far away from the moderating force of oceans, St. Louis is vulnerable to extreme cold, and it is likely that at some point this winter that there will be a stretch of very cold days. 

Snowstorms are most likely on the front and back ends of pushes of cold air. In other words, snowstorms usually form when the cold air enters, and when it departs. Thus, expect sudden bursts of cold air to be accompanied by snow chances, and snow to be possible immediately preceding a warmup. Since the coldest blasts will be concentrated between the end of January and early February, expect the most snow chances during this period.

St. Louis is also in an area conducive to ice storms. Despite being far from the moderating effects of the coast, Gulf air can protrude the upper levels of the troposphere while cold temperatures remain in the lower layers. This can cause freezing rain, or ice events. Ice events are possible all throughout the winter, but the period with the highest risk for these storms is late February as the Gulf air warms but northern cold blasts can keep temperatures at the ground low enough. 

Here are the key takeaways: Conglomerating the winter months, temperatures will be slightly above average and precipitation should be seasonably low but above average. There will be some snowfall chances, especially in the late January-early February period. However, do not expect major early winter or late winter snowstorms. By late February, ice storms will be a threat, followed by a warm up to usher in the severe thunderstorm season that peaks from March to June. 

For winter lovers like myself, keep your hopes up. Sometime soon, pink sunsets will be replaced with white snow skies, and sweatshirts will make way to winter coats!