A Satellite image showing the Northeast of the United States blanketed in snow.

How is Cold Weather Changing?

During any year, cold temperatures, snowstorms, and blizzards can happen. As Earth gets warmer, it does not mean that it will never snow or freeze. It means that over time it will happen less often. Across the planet, days and nights are generally hotter than they used to be.

Brrrrr! Why’s It So Cold Outside?

The landmass of the northeastern U.S. and parts of eastern Canada are covered in white from snow. The outline of the states of the northeastern U.S. and providences in eastern Canada are in black. The states are labeled in black and are listed from bottom to top as Pennsylvania, New Jersey, New York, Connecticut, Massachusetts, Vermont, New Hampshire, and Maine. The state of Rhode Island is also shown, but not labeled. The eastern Canadian providences of Ontario and Quebec are also labeled in black and are located above New York and to the left of Maine. There is dark green-blue water next to the northeastern U.S. coastline. There are white clouds to the right of the water, covering some of the water.

NASA’s Aqua satellite took this image of snow covering the northeastern U.S. in January 2022 after a blizzard traveled through the area.

NASA

Grab your mittens, coat, and hat: winter is back!

Winter for many of us often brings colder temperatures, gray skies, and sometimes snowy days. But in recent years, some winters have felt warmer. In some places, maybe you only needed a winter coat for a few days or weeks. Then in other years, it’s freezing for what feels like weeks on end. What gives?

To answer that, we need to know about the difference between weather and climate.

Weather is what happens day to day: The change in temperatures, cloudy or clear skies, and whether it’s raining or snowing.

Climate is what you get when you put all the weather days together and see what they have in common. This can be over a season or longer, and it can change from place to place. For example, it tends to be hotter in the summer and cooler in winter. Another example is how some places get lots of rain and others do not, like rainforests and deserts.

There are two illustrations. One the left is three blue rectangular boxes with a different outfit in each box. The first box has a blue baseball cap above a black and white striped shirt with blue pants overalls over it, and purple and white sneakers. The second box has a purple sleeveless dress above purple and tan sandals. The third box has a blue, white and purple winter hat, orange winter puffy coat, blue jeans, and tan colored winter boots. Above it is labeled 'Each day’s outfit' and below is labeled 'Weather.' On the left is an illustration of clothes in a closet. On top of a gray shelf are a blue baseball cap and pink, white and blue winter cap. Hanging on a white bar are several clothes, including a blue winter sweater, orange winter puffy coat, a black and white striped shirt, a green striped shirt, a light blue and white dress, blue jean overalls, and blue jeans. There is a gray three-drawer chest on the left of a blue carpet. Next to them are four pairs of shoes. There are purple and white sneakers, tan sandals, tan winter boots, and yellow rain boots. The walls of the closet are blue. Above the illustration is labeled 'Closet of clothes,' and below is labeled 'Climate.'

Weather and climate are similar but not the same thing. Think of your clothes. What you wear each day is like the weather. It changes from day to day. However, all of the clothes in your closet for either winter or summer are based on the climate. For example, you may have mostly shorts in your closet for summer and mostly pants for winter. That’s because climate tells us what the weather will be like most days during a season or longer.

NASA/JPL-Caltech

Earth’s climate is changing and impacting the planet’s temperature, weather patterns, and ocean. When scientists look at Earth’s temperature each year for the past 100 years or so, they see that it has been getting warmer. Across the planet, this means more days and nights are hotter than they used to be.

However, this warming does not mean that it will never get cold where you live. For many places, a blizzard, snowstorm, or freezing temperatures can and do happen each winter. That’s because weather and climate are different things. And the weather is affected by many things.

For instance, it may seem far away, but the weather and climate in the Arctic can actually affect our weather in the U.S. It can change how much cold air moves south and influence how storms travel.

Some changes in the Arctic can happen naturally, while other differences are because of climate change. To monitor changes in the Arctic, scientists began measuring its ice and weather in 1979 with satellites. With this information, they found that the area is warming faster than the rest of the planet because of climate change. This change in the Arctic is leading to fewer cold snaps over the U.S. as time goes on.

There are three square panels with illustrations and text. In the first panel on the left, there is a wavy blue line with a blue color filled in below it labeled 'water.' Above the blue water are four water molecules, which are shown as a larger blue circle with two smaller green circles on each side near the top. Above each molecule is a wavy blue arrow pointing to the top of the illustration. The rightmost arrow says 'wee!' At the top the text says 'Warmer air leads to more evaporation.' The middle illustration shows nine water molecules of different sizes. Two say 'Hi!' and one says 'Welcome!' On top it says 'Evaporation adds moisture to the air, and warmer air can hold more moisture.' The illustration on the right has two white clouds that are touching. The one on the left has one water molecule with a blue arrow pointing to the bottom left corner. It says 'Whoa!' Next to it and below the other cloud are blue raindrops. At the top it says 'More moisture can lead to heavier rain and snow fall when it happens.' All three illustrations have a light blue background.

As air temperatures get warmer, they affect the water cycle. Warmer air leads to more evaporation, which is the changing of liquid water into a gas. The gas form of water is called water vapor. The evaporation adds moisture to the air, and warmer air can hold more of it. This leads to heavier rain and snowfall when it happens, as there is more water vapor in the air to condense, combine, and fall. Condensation is when a gas (water vapor) turns into a liquid (water droplet).

NASA/JPL-Caltech

There is another way climate change is impacting cold weather. As the planet warms, the air can hold more moisture. That can lead to heavier snow and rainfall than usual. It can also change patterns for where it rains and snows. That’s why some places are getting more snow than they used to, even though the planet is warming.

How do we know what’s happening on our planet? Well, satellites and weather stations are keeping track of Earth’s temperatures and more. This provides scientists with important data they need to predict weather and changes to Earth’s climate.

There will likely be fewer cold days in our future due to global warming. That being said, many places will still have at least some cold days in winter. So make sure to hang on to those warm winter coats and long underwear, too!