How to Make a Simple Barometer and Predict the Weather with Kids

Build a homemade barometer with your family using everyday materials to measure air pressure and predict weather changes together.

  1. Gather Your Materials. You'll need a wide-mouth glass jar, a balloon, a rubber band, a drinking straw, tape, an index card, a marker, and scissors. All of these items are probably already in your home. Choose a clear glass jar so you can see the balloon moving inside easily.
  2. Build Your Barometer. Cut the neck off the balloon and stretch the remaining piece tightly over the mouth of the jar like a drum. Secure it with the rubber band, making sure there are no air leaks. Tape one end of the straw to the center of the balloon so it extends horizontally like a pointer. The straw should be parallel to the table when the jar sits upright.
  3. Create Your Measurement Scale. Tape the index card vertically to a wall or heavy object so the straw pointer nearly touches it when your jar sits nearby. Draw a horizontal line where the straw points and write 'START' next to it. This will be your baseline. Add marks above and below this line, spacing them about a quarter-inch apart.
  4. Take Daily Readings. Place your barometer in the same spot each day, away from heating vents or windows. Mark where the straw points on your scale and write the date. Also note the weather outside - sunny, cloudy, rainy, or stormy. After a week, you'll start to see patterns between the straw's position and weather changes.
  5. Read the Weather Signs. When air pressure increases (high pressure), it pushes down on the balloon, making the straw point up on your scale. This usually means fair weather is coming. When air pressure decreases (low pressure), the balloon puffs up slightly, making the straw point down. This often signals storms or unsettled weather within a day or two.
  6. Make Weather Predictions. After collecting data for two weeks, you can start making predictions. If the straw has been pointing down and suddenly moves up, expect improving weather. If it drops from a high position, prepare for possible rain or storms. Remember that weather prediction takes practice, and your homemade barometer works best for short-term forecasts.