Plum Rains, Typhoons, and Dehumidifying: Managing Humidity for Tea in Taiwan

When it comes to storing pu'er in Taiwan, the question we hear most isn't "how many years?" but "what do I do when it's this humid?" The answer lies in a few numbers: the recommended humidity for storing pu'er, and how far Taiwan's actual humidity through the year is from it.

Just How Humid Is Taiwan?

According to Central Weather Administration climate averages for 1991–2020, the monthly average relative humidity at the Taipei station is:

The annual average is 75.0%, and monthly average temperatures range from 16.4°C in January to 29.9°C in July. Annual averages at other stations over the same period are all between 74% and 77%: Taichung 74.5%, Kaohsiung 75.0%, Hualien 77.3%, Hsinchu 76.9%.

These are averages for whole months. In reality, the continuous overcast rain of spring, the May–June plum rains (Taipei's June average rainfall is 345.0 mm), and the muggy days around typhoons often keep humidity above 80% for days at a time. For climate differences across northern, central, and southern Taiwan, see Taiwan's Climate Zones and Tea Storage.

What Humidity Should You Aim For?

Yunnan's local standards mostly set 70% relative humidity as the upper limit for storing pu'er, and the China Tea Marketing Association recommends about 55%–75%. One study stored raw tea at three humidity levels (45%, 60%, and 75%) for a year and found that the tea transformed most smoothly when its "water activity" was between 0.60 and 0.70, with unpleasant smells starting to appear above 0.70. Water activity can be thought of as the humidity at which the tea and the surrounding air reach equilibrium; 0.60–0.70 corresponds roughly to 60%–70% ambient humidity.

So the goal at home is relative humidity of about 55%–70% and a stable temperature between 20 and 28°C, matching the recommendations in Temperature and Humidity for Storing Pu'er. Compared with the table above, Taiwan is at or above that line almost every month, and that's why dehumidifying matters.

Should You Run a Dehumidifier?

Yes, at least in the room where you keep your tea. A dehumidifier is the most practical tool for storing tea in Taiwan. A few guidelines:

• Set it around 60%–65%: there's no need to go below 40%. Too dry and transformation slows right down, and the aroma tends to go flat.
• Don't put tea in front of the outlet: a dehumidifier blows out dry, warm air, and blowing directly on tea dries it out unevenly.
• Close doors and windows: running a dehumidifier with the window open is like trying to dehumidify the whole city.
• Empty the tank often: when it fills up and shuts off automatically, humidity climbs back quickly.

What to Do in the Plum Rain Season

The plum rain season and the days around typhoons are when tea needs the most attention all year:

1. Keep the dehumidifier running and check the hygrometer once a day.
2. Open boxes less: don't take tea out to air in damp weather; wait for dry weather to sort through it.
3. Check boxes against walls and on the floor: the bottom boxes and those against exterior walls are most likely to get damp.
4. Smell it: move any tea that smells stuffy or musty somewhere dry to deal with it separately.
5. After a typhoon: humidity often stays high after the rain stops, so keep dehumidifying for a few more days.

Dry, crisp weather in autumn and winter is a good time to open boxes, sort through your tea, and let it breathe.

Where to Put the Hygrometer

Inside the tea box or cabinet, not in the middle of the room. The humidity in the room and inside a cabinet can differ by several percentage points; the space closest to the tea is the humidity the tea actually experiences.

• Put one in each place you store tea for more accurate readings.
• Place it at mid-height in the box, not against the bottom or sides.
• Record the reading once a month along with how the tea smells, and after a year you'll see your home's patterns.

Can Desiccants Be Used?

Yes, if used correctly.

• Silica gel moisture absorbers: clean and leak-free, they can go in a corner of a tea box or cabinet. Replace them when they change color, or dry them for reuse according to the instructions.
• Two-way humidity control packs: packs that hold humidity at a fixed level are available; choose ones rated around 62%–69% for sealed storage boxes or tea cabinets.
• Calcium chloride dehumidifier boxes: they collect liquid as they absorb water and could soak your tea if knocked over. Put them at the bottom of a cabinet, not in the same box as tea.
• Don't over-dry: too much desiccant in a small sealed box can drop humidity below 40%, which stalls transformation.

Desiccants are a supplement; dehumidifying the room is the real solution.

Can Tea Be Kept in an Air-Conditioned Room?

Air conditioning dehumidifies as it runs, so an air-conditioned room is usually drier than other rooms in summer, and it can hold tea, but watch two things:

• Avoid the vent: cold air blowing directly on a tea box cools its surface, and with a big temperature difference, moisture can condense.
• Temperature swings: in a room where the AC is on by day and off at night, humidity and temperature rise and fall sharply, and humidity climbs quickly once the AC is off. Ideally, pair it with a dehumidifier to keep the environment stable.

Stability matters more than low temperature. A room that holds steady at 26°C and 60% suits pu'er better than one at 22°C by day and 30°C at night. The overall style of Taiwan storage is in Taiwan Storage.

FAQ

How should pu'er be stored during the plum rain season? Keep a dehumidifier running in the room where you store tea, hold humidity below 70%, open boxes less, check the hygrometer daily, and check boxes against walls and on the floor.

Do I need a dehumidifier to store pu'er? Annual average humidity across Taiwan is about 74%–77%, so we recommend it, set around 60%–65%, with tea kept away from the outlet.

Where should the hygrometer go? Inside the tea box or cabinet, at mid-height, with one in each place you store tea.

Can desiccants go in a tea box? Silica gel moisture absorbers or 62%–69% two-way humidity control packs work; calcium chloride boxes collect water and shouldn't share a box with tea.

Can pu'er be kept in an air-conditioned room? Yes, since air conditioning also dehumidifies; but keep it away from the vent and avoid big swings from running the AC by day and switching it off at night.