Temperature
Temperature is the variable that splits the category in two. Light, unroasted oolongs want cool conditions, ideally 5 °C if you are keeping them for months. Roasted oolongs want room temperature, roughly twenty to twenty-five °C.
The reason is the roast itself. A freshly roasted oolong goes through a settling period of one to six months during which the fire note softens. Cold storage slows that settling down, which is the opposite of what you want.
Steady matters as much as cool. A cupboard that swings between ten and thirty °C over a week is harder on leaf than a constant 25 °C, because every swing moves moisture in and out of the packaging.
If you have one space and two kinds of oolong, put the light ones somewhere cooler and leave the roasted ones at room temperature. That single split covers most of what temperature can do for you.
A thermometer in the cupboard is worth the small cost. Most people are surprised by what their tea shelf reads in July, and the reading is usually enough to prompt a change without any further argument.
Humidity
Humidity is the one to control at the leaf rather than the room. Finished oolong sits around three to six percent moisture, and it will move towards the humidity around it if the packaging lets it.
A relative humidity of fifty to sixty percent is comfortable for storage. Above about 70 percent, the risk of mould climbs quickly, especially for roasted leaf that has been re-fired and has open surfaces.
In a humid climate, the answer is packaging rather than a dehumidifier. A vacuum-sealed foil pouch or a tin with a real gasket keeps the leaf at whatever moisture it had when it was packed.
Do not add desiccant packs to a tin of oolong unless the seller did. Over-drying leaf makes it brittle and hollow, and the cup loses body long before it loses aroma.
Light and air
Light matters more for oolong than most people assume, because a lot of the aroma sits in compounds that break down under ultraviolet. A clear jar on an open shelf is the classic mistake.
Air is the other half. Oxygen drives the slow reactions that eventually flatten a light oolong, and it also carries odours into the leaf. A tin that is airtight solves both at once.
Odour is worth naming separately because oolong is often stored near other teas. A roasted oolong next to a smoked one, or any tea next to coffee or spices, will pick up what is in the air.
The practical rule is opaque, airtight, and nothing strongly scented in the same box. A cardboard box of mixed teas on a kitchen shelf fails all three at once.
The target environment
For light oolong: sealed, opaque, 5 °C, and drunk within 6 months. A vacuum pouch in the door of a fridge is workable, though a cool cupboard is steadier and avoids condensation on opening.
For roasted oolong: sealed, opaque, twenty to twenty-five °C, and given one to three months to settle before you judge it. After that it holds well for 2 years or more without special care.
For aged oolong: sealed, opaque, room temperature, and checked once a year. You are managing a slow process rather than preventing one, so consistency matters more than any single number.
Humidity stays between 50 and 60 percent in all three cases. If you can hold temperature and humidity inside those bands, the rest of the setup is just packaging.
Write those three lines on a card and keep it where you store tea. The numbers are not complicated, and having them in front of you settles most of the arguments people have about refrigeration.
Adjust through the year
The environment you can control changes with the season, and the useful move is to notice when it changes. A cupboard that is ideal in winter can be the warmest place in the house in July.
In a hot, humid summer, shift light oolongs to the fridge and leave roasted ones where they are. The fridge is a problem for roasted leaf, because cold slows the settling you are waiting for.
In a dry winter, do nothing. Dry air is not a threat to sealed leaf, and opening tins more often to check on them does more harm than the air does.
If you take a pouch out of the fridge, let it come to room temperature before you open it. Opening cold packaging in a warm room pulls condensation onto the leaf, and that water goes straight into the tea.