Is it chilly where you live? When it starts to get colder outside, you may hear weather forecasters talk about a cold front moving into your area. Have you ever WONDERed what they’re talking about?

In weather terms, a front is the boundary between air masses of different temperatures. A cold front is the leading edge of a mass of cooler air that is pushing warmer air ahead of it out of the way.

As a cold front moves into an area, it displaces warmer air at ground level. Colder air is denser than warm air, so it pushes the warm air higher into the atmosphere. Temperature changes along the boundary of the cold/warm air can be in excess of 50° F.

As the warm air rises, it causes an area of low pressure along the cold front. The warm air cools as it rises and moisture begins to condense.

If enough moisture is present, a narrow line of thunderstorms and rain can form along the edge of the cold front. If the cold front boundary is unstable, thunderstorms are more likely. Stable systems often just bring steady rains. Very unstable cold fronts can generate hail storms and even tornadoes.

Cold fronts usually move from northwest to southeast. They tend to be strongest in the spring and the fall and weakest in the summer. In addition to rain and thunderstorms, they also bring gusty, shifting winds.

Winter cold fronts might not generate any precipitation at all if there’s insufficient moisture in the air. If there’s moisture in the air, though, a cold front can bring significant snowfall.

Cold fronts move much faster than warm fronts and can cause sharper changes in the weather. As a cold front is passing through, you will notice temperatures drop quickly and then steadily decline as it passes.

If you’re watching the weather forecast on your local news, a cold front will be marked by a solid blue line. The blue line marking the cold front might also include triangles pointing in the direction the cold front is moving.

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    • Happy Monday, Wilber! Thanks for sharing your personal connection to today’s Wonder! We thought it was AWESOME to learn about cold fronts and we hope you did, too! :-)

  1. Dear Wonderopolis,

    We enjoyed learning about cold fronts today. We saw on the news this morning that a cold front is coming our way.

    We think tomorrow’s wonder might be about presents and the holidays.

    Thank you for the wonders,
    Mrs. Tillman’s 4th graders

    • Hello from Wonderopolis, Mrs. Tillman’s 4th grade class! We’re so glad you guys enjoyed learning about cold fronts with us today! Weather can be FUN to WONDER about! :-)

    • We’re proud of you for WONDERing more about cold fronts after you explored today’s Wonder of the Day® about them, Kira! Thanks for being such a GREAT Wonder Friend! :-)

  2. HEY. I live in Illinois and it is cold with no snow, but hopefully we get lots of snow. My dad is a snow plow driver and heavy equipment operator for I.D.O.T: Illinois Department Of Transportation!

    • Thanks for sharing about the weather in your part of Illinois, Hunter, and also for sharing about your dad’s cool job! We think it would be FUN to drive the machinery that helps clear the roads and makes it safer for people to travel! Please tell your dad that your friends in Wonderopolis think he ROCKS! :-)

    • We feel the exact same way, aterrell! Thanks for letting us know you liked learning about cold fronts today…meet you back here in Wonderopolis tomorrow for more WONDER fun, OK? :-)

  3. Our class is experiencing beautiful sunny, winter weather here in Northern California.

    One question for you…Why is it that some of your links to past videos are not working?

    Thanks, we love your Wonder of the Day.

    • Hi there, Mrs. Walker’s Fifth Grade! We bet it’s a WONDERful day in Northern California! Thanks so much for sharing about the weather where you guys live!

      We like to pair all sorts of neat videos with our Wonders of the Day here in Wonderopolis. Sometimes, the owners of the videos on YouTube or Vimeo might delete their accounts or change the permissions for their videos after the Wonder has been shared. We double-checked the links in today’s Wonder and see that the video that goes with our “tornadoes” link isn’t working. Thank you SO MUCH for bringing this to our attention with your comment! We are on the case and will be getting a new video up soon! :-)

    • Thanks so much, Grace W! We are so lucky to have great Wonder Friends like you! Wonderopolis celebrated its second birthday on October 4th this year! We are part of the National Center for Family Literacy, an organization that supports our Wonders each and every day. We have Wonder Friends all over the place who share their ideas, find cool videos and help spread the Wonder to SUPER people, just like you! :)

  4. Dear Wonderopolis,

    Thank you for the wonderful wonders, we think tomorrow’s wonder will be about presents and/or Christmas, or even Santa.

    Mrs. Witkowski’s 4th graders

    • Hi there, Wonder 4th graders in Mrs. Witkowski’s Class! We are so glad you stopped by Wonderopolis to have fun today! Thanks for leaving a comment filled with your guesses for tomorrow! We can’t wait to find out what they will be! :)

    • Even though the weather isn’t pretty, we hope you’re staying sunny (and dry) in Michigan, Wonder Friends in Mrs. Jones’ class! Thanks for sharing your SUPER guesses with us… we can’t wait to find out what tomorrow’s Wonder of the Day® will be! :)

  5. Hello Wonderopolis!

    Today’s wonder got us wondering how we could draw a picture that would make people feel cold. We drew lots of winter things like storms, snowmen, ice, mittens, and snow. We even used colors that made us feel cold, like grays, blues, white and black.

    We made it feel so cold in the Lab today, our teacher had to put on his jacket to stay warm!

    • Hello PB Kindergarteners! We think you’re right on track– storms, snowmen, ice, mittens and things that make you chilly are excellent places to start! We bet your art is beautiful, but makes you want to drink hot cocoa!

      Thanks for sharing your cool comments with us, and sharing your drawings on twitter, too! :-)

  6. Today’s wonder was really cool! It was very interesting to learn that a cold front can cause storms.I think that there was a cold front moving in a few days ago where I live, because there was really strong, cold wind. Thank you for today’s wonder! It was great! :)

  7. Hey wonderopolis,

    I loved today’s wonder. In California, today was quite a sunny day. It was 80 degrees! But sometimes I wish, it would snow. That would be my dream come true.

    Bye Bye :)

    • Hey Wonder Friend Cherry! We bet it’s lovely in California, but we can imagine it would be nice to see snow once in a while! We bet it would be cool to switch locations with a Wonder Friend on the Northeast coast– they have seen a few snowflakes during this time! Or Wonder Friend Sara… she’s got enough snow to share! :)

  8. Hi I live in the southern part of Minnesota. Where we are getting a lot of snow so much snow my older sister can’t even get 5 feet form the garage. But lucky for me NO school. So I know what a cold front is. Thanks and I think tomorrow it should be why are people left handed. And I’m left handed myself. Thanks bye

    • Hi there, Wonder Friend Sara! We hope you are staying warm in Minnesota! We are glad to hear that although you’re not in school, you’re still WONDERing with us! We feel so lucky! We think you and Wonder Friend Cherry could swap places for a day– and you’d both be happy!

      We’ve got a Wonder you might enjoy, as a leftie: Wonder #328– Why Are Some People Left-Handed? http://wonderopolis.org/wonder/why-are-some-people-left-handed/ :)

  9. We just reviewed and took our fonts test last week. We’re just reviewing for our chapter quiz tomorrow!
    Sincerely Danielle :)

    • What great timing, Danielle! We are so glad to hear that this Wonder was a perfect match to your lesson! Fonts are AWESOME to Wonder about! Good luck on your chapter quiz! :)

    • Hey there, Kool Junior! We hope you try that experiment, with the help of a teacher, adult or parent! WONDERing is so much fun! :)

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Have you ever wondered…

  • What is a cold front?
  • Does a cold front always bring precipitation?
  • When are cold fronts most common?

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Cold FrontVimeo Video

Try It Out

Do you keep an eye on the weather? Some people like to watch the weather forecast every day and then see if the weather forecaster was right or not. Some people watch weather shows on television like they were primetime shows!

Whether (pun totally intended) or not you usually keep track of the weather, try to keep a weather journal for the next week. Each day, find out what the forecast is by watching a local weather report or looking it up online.

Then watch and see what happens with the weather. Record the high temperature, low temperature and whether or not you got any precipitation (rain or snow). How accurate is your local forecast from day to day?

Have fun keeping track of the weather! You never know when a career in meteorology might be in your future!

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National Geographic Xpeditions’ How’s the Weather Today? lesson asks children to think about the weather in their area and introduces them to weather and temperature trends at different latitudes.

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