At some point or another when discussing grind adjustment (as one does), you will probably have heard a coffee professional say that even humidity can effect how your coffee is extracting at a particular time of the day.
And yes, unbelievable as it may seem, your coffee is that
sensitive to its environment. Did you turn on the aircon half way through the day? That will change how your coffee is extracting.
We get a lot of calls from people for a lot of coffee related queries, this particular one was looking at a grinder that just wasn't grinding. The motor was going on but even on an extremely coarse grind setting they were having no joy.
So we got involved, unscrewed all the bits to release the burrs only to find that they were completely clogged full of compacted coffee granules. On the recommendation of another coffee friend we requested a hairdryer (fun!) and proceeded to dry out the grinds and then a paper clip to scrape out the remaining grinds caught deep in the burrs, then vacuumed those bad boys up. (Pro tip, if you can help it avoid using water to clean burrs)
So now the burrs were shiny clean, and now the grinder was working, but we still we couldn't figure it out, the grinder was new, why would they have so quickly become clogged? We inspected the beans; they were a relatively dark roast and quite oily but nothing extreme.
The answer came to us as Jane walked in and asked to make a cup of tea, so she switched the kettle on that lives right next to the grinder while we continued to test. And suddenly the answer became clear. As the kettle boiled the steam billowed out of the spout directly over the coffee station and grinder. Steam was causing all this trouble!!! So we moved the kettle away from the coffee station and hey presto, no problems since!
This is an extreme example of humidity and the atmosphere effecting the coffee and the equipment! The steam settled on the burrs and the coffee got wet and compacted in the grooves of the burrs, rendering it useless!
So be aware that the atmosphere is having an effect on those beans of goodness.