Storing Matcha
Storing matcha can be a bit of a confusing affair - different companies and products have different instructions. Exposure to heat, air and moisture can affect the quality.
Most of the products I review say to store it in the fridge. In my case, I keep these in a closed compartment in the fridge door (especially after opened) and I'm very careful not to do anything that alters the taste before or during the review.
I keep unopened matcha in a cupboard, and some that have no instructions or where I don't care too much about oxidizing (gets used up fast, or is a cheaper product, for example). My Cha-Do is always in the cupboard, because it's my default. You could, however, store unopened matcha in the fridge or freezer, too.
I also now have two matcha that say to not store it in the fridge when in use because pulling them out of the cold to extract the powder can cause condensation. A workaround they offer for this is waiting to let it reach room temperature before opening - this also goes for unopened ones you're now pulling out to open.