Have you ever noticed the coffee doesn't flow quite right from your machine when the weather changes? Believe it or not, ground coffee is affected by weather conditions. The weight of ground coffee can change according to the weather and your grind will need to be adjusted according to that weight. Generally speaking when it is hot or humid you will need to make your grind coarser or your cup of coffee will be under extracted. So therefore when it turns cold, you may need to make your grind finer so you don't get an over extracted cuppa. Of course making sure you are tamping properly is another thing that will affect over or under extraction, so we might talk about tamping next time!