Coffee Loses Flavor to Air, Light, and Heat — Fast
Roasted coffee beans are full of volatile aromatic oils that start escaping the moment they're ground, and even whole beans degrade within a couple of weeks of roasting once exposed to air. An opaque, airtight container away from the stove or a sunny counter slows that loss considerably; the fridge or freezer isn't necessary and can introduce condensation when you take coffee in and out, which actually speeds staling. Buy smaller amounts more often and grind just before brewing if you want coffee that still tastes like something.
Sources & methodology: These tips draw on established food-science references —
Harold McGee's food-science writing, America's Test Kitchen /
Cook's Illustrated testing, Serious Eats'
technique reporting, USDA food safety guidance,
and peer-reviewed food-safety research (including UC Davis
cutting-board studies) — not reworded recipe-blog consensus.