When it comes to drying cannabis, most growers are already working with a familiar set of tools: temperature, relative humidity (RH), airflow, and time. These variables have long defined best practices, and for good reason: they’re measurable, controllable, and proven.
Lately, though, another term has been drifting into the conversation: dew point.
It’s a concept borrowed from weather science, and some growers are starting to ask whether it offers a more precise way to understand drying conditions. So the question becomes: does dew point actually matter in the dry room, or is it just another layer of complexity?
What is dew point anyway?
Dew point is the temperature at which air becomes fully saturated with moisture. That means it can’t hold any more water vapor and condensation begins.
In everyday weather, dew point is used to describe how much moisture is actually in the air. When the air temperature drops to the dew point, you get dew, fog, or condensation on surfaces. Higher dew points mean more moisture in the air and that familiar “muggy” feeling, while lower dew points feel dry and crisp.
Unlike RH, which changes as temperature rises or falls, dew point reflects the actual moisture content in the air, making it a more stable way to think about humidity in outdoor conditions.
In cannabis drying, dew point is sometimes used as another way to interpret the relationship between temperature and humidity in a controlled environment. It represents the same underlying conditions growers are already managing through ambient conditions, relative humidity, and active or passive control methods.
If you want a deeper breakdown of those humidity concepts and how they apply across cultivation and storage, check out our article on the best humidity for cannabis from seed to storage.
How to measure the dew point
Calculating dew point manually isn’t something most growers are going to do, and realistically, you probably don’t need to either.
At its core, dew point is calculated using temperature and RH. Those two inputs are run through a formula (most commonly the Magnus equation) to determine the temperature at which the air would become fully saturated.
That formula gets complicated quickly. The important part is this: if you know your temperature and RH, you already have everything needed to determine dew point.
Most growers who track it rely on tools that calculate it automatically, including digital hygrometers, environmental monitors, and climate control systems. These devices measure temperature and relative humidity in real time, then handle the math in the background.
It’s also worth noting that dew point isn’t usually measured directly without a chilled mirror hygrometer. It’s more often derived from the same environmental data you’re already using, which is why many growers focus instead on tracking moisture more directly, whether in the air or in the plant itself.
How to increase the dew point in a controlled environment
Increasing dew point means adding more moisture to the air.
You can do this by:
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Running a humidifier
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Reducing the introduction of drier outside air
How to decrease the dew point in a controlled environment
Decreasing dew point means removing moisture from the air.
You can do this by:
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Removing moisture from the air (e.g., dehumidification)
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Exchanging air with drier incoming air
Why do growers care about dew point?
Thinking in terms of dew point can be a helpful way to visualize what’s happening in the drying room, especially for growers who are used to interpreting weather conditions.
It essentially translates temperature and relative humidity into a single idea: how much moisture is actually in the air.
For some, that mental model makes it easier to understand drying dynamics at a glance.
Why the traditional measure matter more
While dew point can give us some useful context, it doesn’t replace the core variables growers actually control: temperature and relative humidity. Those are the levers in the room.
Some argue that RH is less useful because it’s derived from temperature and moisture levels. But in a controlled drying environment, that’s exactly why it works. Growers are already managing both inputs, so RH remains a practical and reliable way to track conditions.
There’s also an important difference between outdoor weather and indoor drying. Outside, dew point can swing throughout the week as air masses change, fog rolls in, or overall moisture levels shift.
In a drying room, conditions are intentionally stable. You’re not reacting to nature, you’re controlling the environment. That stability makes temperature and RH not just sufficient, but ideal.
If your drying process is already dialed in using those two variables, adding dew point into the mix may provide another perspective, but it isn’t necessary.
