Coffee bubbles


The next time you pour your morning coffee, pay attention to the bubbles that form on top.  Some people believe that the pattern the bubbles create can predict the weather.  Now I know for some of you this is going to be a difficult task because you can’t even see straight before that first cup, but do try this fun experiment.  It might even start your day off with a little humour.  For most of us that would be a definite improvement over how they usually start.

First of all, your coffee cup has to have straight sides.  If the sides flair out at the top it won’t work as well.  You might want to get this cup ready the night before and place it near

the coffee pot so you can find it in the morning.  You might also want to get out a pen and paper so you can write down what your observations are and keep track to see if the predictions work out.  The geeks out there can use their ipad or notebook if they wish, however, don’t hold me responsible if you enter gibberish before having your first coffee.


Now, pour your coffee and watch the bubbles.

If the bubbles amass in the centre, you are in a high-pressure system.  High air pressure during fair weather will make the surface of the coffee slightly concave so that the bubbles will slide into the middle of the cup.  So it’s going to a beautiful day!

If the bubbles move to the edge of the cup rather quickly, it’s also a good sign.  Expect clear skies for the next 12 hours.

On the other hand, low air pressure during foul weather will make the surface of the coffee slightly convex and the bubbles will slide down and form a ring around the cup.  You can then expect rain in the next 12 hours and can start packing your rain gear!

If the bubbles slowly move to the edge of the cup, you may get a bit of weather, but it should be clearing in a few hours.

If you have managed to make a cup of coffee without bubbles, simply flop a spoonful of coffee back into your cup and make some more bubbles.


The theory behind this trick is that high pressure will push the bubbles to the edge, and high pressure indicates a period of sunny, calm weather.  Low pressure won’t move the bubbles and low pressure systems typically bring unsettled weather.


Most people believe it isn’t.  They argue that there are so many variables when making coffee that the above experiment can’t possibly be true.  Temperature of the water, type of coffee, concentration of coffee, etc., when combined with the high pressure, bubbles will push to the edge, so it can be illogical to link the position of the bubbles to the weather at all.

Either way, it is an interesting experiment that you might like to try.  Even if it doesn’t work, you can use it as an excuse to have another cup of coffee.


Apparently this will also work with hot chocolate so you might want to make some for the kids and try the experiment with them.